Rooted your Android smartphone/tablet or changed the ROM,
but now want to go back to genuine firmware? Darren Yates shows you how
using the Samsung Galaxy S3 phone.
Rooting
your phone and even trying out new ROMs is part and parcel of being a
hardcore enthusiast. Ditching the corporate bloatware from phone network
providers — the prime reason for rooting — is tantamount to ditching
the corporate advertising and getting your phone back. But community
ROMs don’t always match the hype, particularly when it comes to
extracting your phone’s full features list.
It’s usually then that
some decide they’d rather go back to what they had. If you’re running a
Samsung Galaxy S2 or S3 phone and you’ve tried the latest CyanogenMod
ROM, you might be missing the ability to connect your phone to your TV,
for example.
So the big question is: can you put your phone back to the way it originally was?
Yes, you can go back
It’s
easy to get a bit caught up in the advanced nature of rooting and
flashing your phone, and see it all as a bit of a dark art. But if you
remember your phone is just a portable Linux computer, changing ROMs
becomes changing the OS and it suddenly seems less daunting.
The
best rule of thumb for changing a ROM in your phone is to always be
methodical in what you do, never panic and give your phone time to do
what it needs to do.
In very simple terms, bringing your phone
back to original condition is all but the same as putting a new ROM on
it — because that’s exactly what you’re doing. However, there are
several ways to do it, depending on where your starting point is.
Danger, Will Robinson!
Flashing
your phone will null and void your warranty. While we have successfully
tested the processes described in this story, we offer no support or
guarantee. You try them at your own risk.
First things first: Back up everything
It
should become as second nature as breathing — any time you change your
phone’s ROM, back up everything. Storage is cheap; getting data back
that you haven’t backed up isn’t. We use two methods. First, we use the
‘Recovery Mode’ Nandroid backup to make a complete backup of the phone,
which is basically a snapshot of the phone as it is. Second, we use
combinations of Android apps to back up the phone — we sync email,
contacts and calendar with Google Sync and back up SMSs with SMS Backup
and Restore.
We don’t normally back up apps as they can be
restored from Google Play. We’ve never had much luck restoring apps when
changing from one OS to another — not surprising, really. You probably
already know how much Windows likes to be copied from one computer to
another. Anyway, the general idea is to back up everything and copy the
backup files to your PC — don’t leave them on your phone.
Method #1: Nandroid backup
If
you were a good APC reader and performed a Nandroid backup before you
flashed the new ROM, you can just back up your personal data (email, SMS
and so on) and restore that Nandroid backup. The downside is, you’ll be
sending your phone back in time to the point you made the backup, as
everything after that date will disappear from your phone until you
reinstall them from your new backups. This method basically returns your
phone to its previous ROM.
Method #2: Install a new stock ROM
If
you forgot to do a Nandroid backup or it hasn’t worked, all isn’t lost.
Another option would be to take the latest available stock ROM from
your phone’s manufacturer or your network provider and install that onto
your phone. The downside here is that most stock ROMs are a generation
(or possibly two) behind the latest available release. For example,
Optus just released its Android 4.1.2 ROM for the Galaxy S2 in late
March, despite 4.2.2 now being the latest benchmark.
Where to get your ROM
Samsung
is like most phone makers, preferring to deliver new ROMs as
over-the-air (OTA) updates rather than as a downloadable file you
install yourself. However, if you’ve installed a non-stock ROM, the
ability to get updates OTA will likely have been removed. So where can
you download stock ROMs? For Samsung owners, head to
Sammobile. It’s the most complete list of stock ROMs by phone provider we’ve seen for any smartphone, let alone just Samsung mobiles.
Which ROMs?
If
you’re going to get into the habit of flashing ROMs onto your phone, we
think it’s always a good idea to understand exactly what you’re doing.
And when it comes to phone ROMs, there’s more than meets the eye.
When
you load a new OS onto your PC, you’re installing high-level code that
interacts directly with the user. It contains the code that runs your
apps and provides the basic apps like Windows Explorer and so on.
In
your phone, the equivalent is colloquially referred to as the Phone
ROM. It’s the high-level Android operating system you interact with. But
it’s not the only ROM your phone uses.
Your PC’s motherboard has a
low-level firmware called the BIOS (basic input/output system), a code
set that communicates between the hardware and the operating system,
like talking to hard drives and setting the CPU clock speed. Your
phone’s equivalent here is commonly called the Radio ROM and its
function is to handle the wireless hardware electronics in your phone.
However, just to be different, Samsung uses different terms:
- PDA.
This refers to the Android operating system ROM version code, although
it doesn’t obliquely refer to Android in any way (just to make it
easier… not).
- Phone. What everyone else calls the Radio ROM is Samsung’s Phone ROM, handling the modem and wireless connectivity electronics.
- CSC.
This stands for Consumer Software Customisation. It’s a ROM separate to
the PDA ROM, which contains the corporate bloatware specific to your
network provider and your geographic location.
We’ll talk
more about these later, but for now, it’s just enough to understand what
these Samsung terms mean and how they correlate to terms you’ll read
online.
Picking the right ROM
As
we’ve mentioned previously, the most important aspect of picking a
stock ROM is making sure you get the right one for your phone model. If
you have the standard 3G version of the Galaxy S3 as sold in Australia,
its model number should be GT-I9300T (you can find it on the Samsung
splash screen when your phone first boots). The international version is
known as the GT-I9300, while the 4G version is the GT-I9305. And when
you head over to Sammobile, these are the model numbers you need to look
up your model.
The reason it’s so important that you pick up the
right download is because Samsung stock ROM packages include both the
PDA and Phone ROMs (the operating system and the Radio ROMs). So while a
PDA ROM for another phone might work, a different Phone/Radio ROM
probably won’t and will very likely brick your Galaxy.
Beware the bugs
The
other thing you need to be careful of is making sure that you don’t
choose too old a ROM. For example, if you’re running a Galaxy S2, don’t
choose an Android 4.0.4-based ROM, otherwise you could end up bricking
your phone through the Galaxy S2 Superbrick Bug. The S3 isn’t immune
either, with its own Sudden Death bug plaguing Android 4.0.4 ROMs.
Unfortunately, it means we can’t just tell you to get the latest ROM and
you’ll be right — you should try to keep up with phone trends,
particularly your model, and be aware of what’s happening in the market.
In
the case of the Galaxy S2 and S3 phones, new Android 4.1.x-based ROMs
have so far proven to be bug-free and should be your starting point for
stock ROMs.
How to get it onto your phone
ROM flashing has become so sophisticated that there are three different options available for flashing a Samsung phone.
- Recovery Mode. You copy the ROM file onto your phone’s storage and use the phone’s built-in ‘Recovery Mode’ to install it.
- Samsung Kies. Allow Samsung’s official software to detect the phone and grab the latest official phone/network update and install it.
- Samsung ODIN. Grab the ROM and install it yourself via your PC.
Our
preference is to use the ‘Recovery Mode’ or ODIN — we’re just not fans
of Kies. It worked happily enough with our test Galaxy S3, but it’s
never picked up OTA updates with our S2. That said, it’s a
consumer-focused tool so it’s not designed to let you get too funky with
your phone. ODIN is reportedly a leaked internal Samsung app and
potentially more dangerous (because it lets you do dangerous things like
repartition flash storage), but if you don’t stray too far, it’s easy
to use and very effective.
How many times can I flash my phone?
The
NAND flash storage inside your phone can support many hundreds of write
cycles so it’s unlikely you’ll kill your phone’s storage by flashing a
new ROM. The bigger issue comes if you flash a new Radio ROM (the code
that talks to the phone’s wireless connectivity electronics). Flash a
dud Radio ROM and you may well brick the phone. While no-one can give
you an iron-clad guarantee, chances are you’ll have a new phone before
you reach your phone storage’s flash write limit.
Warranty restored?
In
the old days with phones like the HTC Desire, restoring a rooted phone
back to its original condition with a legitimate stock ROM effectively
also restored your phone’s warranty — mainly because there was no way
for the phone provider to tell whether the phone had ever been rooted or
ROM’d in the past.
However, the Galaxy S2 and S3 now have a
built-in custom binary download counter that records how many times the
phone’s storage has been flashed. The idea was that even if you replaced
a community ROM with an official one, Samsung would still know you’d
flashed it in the past, thanks to that counter, if the phone was ever
presented for repairs under warranty.
So the reality here is that
restoring your phone to stock doesn’t restore your warranty if the flash
counter has it registered that you’ve flashed a different ROM at some
point.
Turning back the clock
Winding
back the old mechanical odometer in cars was one of the dodgier
practices rogue used car sellers would use on unsuspecting buyers and
make clapped-out motors seem like they’d literally lived a sheltered
life. Well, it’s also possible to wind back (as in reset) the binary
download counter; however, we don’t recommend it.
There’s an app
on Google Play by the ever-brilliant Xda Developer/moderator Chainfire
called Triangle Away, which attempts to reset the counter. But because
it operates on the phone’s bootloader code that tells the phone what to
launch when it first boots, Triangle Away may brick your phone if it
doesn’t work correctly — not a recoverable brick like an Android ROM
flash gone wrong, but a fully unrecoverable brick that requires advanced
electronics knowledge (JTAG) or a new board to fix.
If you’re
seriously worried about warranty, don’t flash your phone in the first
place. Otherwise, if you’re happy to lose your warranty, there’s nothing
to be gained by resetting the counter, although there’s plenty more to
lose.
You choose
In the
end, it’s your phone — you get to choose which ROMs you install. While
most community ROMs are generally fantastic at removing bloatware, they
don’t always give you your phone’s full features list and a stock ROM,
warts and all, might actually be a better option. There are some good
ROMs based on official releases that maintain functionality, but if you
want to go back to being safe and conservative, a stock ROM is the way
to go.
Step-by-step guide: Install a stock ROM on a Galaxy S3 using ODIN
WARNING:
While this guide was successfully tested on a Samsung Galaxy S3, we
provide no support or warranty on the information provided. Use at your
own risk.
Step 1:
Charge
up your phone to at least 75% capacity. Make backups of your current
phone setup using Nandroid (complete phone backup), Google Sync (email,
contacts, calendar) and SMS Backup and Restore (SMS). If you haven’t
already, install Samsung Kies for its USB drivers — we won’t be using
this software otherwise.
Step 2:
Head to
Sammobile,
search for your phone model and select the version that matches your
location and network provider. Once downloaded, unzip the contents into a
folder on your hard drive.
Be warned:
S3 stock ROMs can be greater than 1GB in size and require up to 2GB to
unzip. You should see a large ‘tar.md5’ archive file after unzipping.
Step 3:
Download the Samsung ODIN 1.85 tool from
tinyurl.com/d8tcnsu (size: 204kb). Unzip it, launch it and with the phone turned off, plug your S3 into your PC’s USB port.
Step 4:
Turn
the phone on into ‘Download Mode’ (press and hold the power, ‘Home’ and
volume down buttons until you see the warning screen). You should see
the phone listed in ODIN. Press the ‘PDA’ button and select the
‘tar.md5’ archive. Ensure the ‘Re-Partition’ box is unticked.
Step 5:
Press
the ‘Start’ button and allow ODIN to flash your phone with the stock
ROM. It’ll take a few minutes but once it’s completed, you should get
the big green ‘PASS’ signage. Your phone should now automatically
reboot.
Troubleshooting
If your phone keeps showing the
Samsung splash screen and rebooting, it’s stuck in a boot loop. Don’t
panic — it’s a common issue. Provided that you got the green ‘PASS’ sign
in step 5, here’s what you can do to fix it.
Step 6:
Pull
the cover off your phone and remove the battery. Put it back in when
the screen goes blank, put the cover back on and boot your phone into
‘Recovery Mode’ (press the power, ‘Home’ and volume up buttons until you
see the Samsung splash screen). When the recovery menu appears,
navigate using the volume buttons to ‘Wipe data/factory reset’ and press
the power button to activate.
Step 7:
When it’s done, navigate back to ‘Reboot Now’ and allow the phone to reboot. It should now come up as normal.
Will a stock ROM keep my phone rooted?
The
short answer is no. By installing a stock ROM, you also remove the root
access because you’re no longer using the same operating system. Think
of it as if you were replacing Windows XP with Windows 8 — you don’t
have the same OS installed so none of the same conditions remain.
However, there’s nothing stopping you from rooting your phone again with
the new stock ROM installed if that’s what you want. (Just follow the
process in our article here on
How to root your Android phone).
Other tips
- If
the flash process failed, check if it passed the MD5 check test — this
checks to see if the download is a valid file. If it failed, download it
again.
- If the MD5 checksum test is fine, try flashing it again.
.webp)
.webp)
.webp)
