Samsung software will no longer burn their mid-night oil to get a new Android OS update for Galaxy S3 owners anymore, but there are developer souls who will do. The result of which are two popular ROMs already been available for the Galaxy S3, model no. GT-i9300, the CM12.1 and the AICP ROM, bringing the latest Android 5.1 update to the phone.

It’s been long since Galaxy S3 went past its two years software-update-guarantee life, and now its two recent updates are work of the user-based unofficial updates. That includes the major one in Android 5.0 Lollipop, the biggest change to Android by any update, and now the Android 5.1 update, also called Lollipop.

What about official update release?

Android 5.1 will never arrive for the Galaxy S3 officially. Samsung has stopped providing software updates to the device.

Benefits and drawbacks of the unofficial update

Benefits are huge when the OEM has stopped the updates for the device. Thus, you get to use the latest and greatest of Android OS thanks to the unofficial updates in custom ROMs, which you would completely miss otherwise. The cool new features, the material design, the lovely animations, etc are few examples of what you could miss if you don’t jump the bandwagon of custom ROMs world. We’re loving every moment with these, btw.

On the drawback side, you need to install a custom recovery, which breaks warranty. There may be few tricks around that install the recovery without breaking the warranty but those are few cases and may not work all the time. But anyway, your Galaxy S3 is probably well past 1-year warranty life and you may not bother about it all, given the huge updates on offer.

Removing the unofficial update?

Simply install the Samsung firmware back using Odin PC software, and you’ll be back to last official update from the company.


Note: Keep in mind that this is not an official Samsung Android 5.1 update firmware, and is a work of a user, hence you may have to face bugs and issues now and then.

Update: April 6, 2015

The Samsung Galaxy S3 has received more love from developers as regards Android 5.1 update, and we’ve come to know that because one more 5.1 update toting ROM has been released for the device. Called the AICP ROM, it represents one more option when it comes to Android 5.1 update for users of Galaxy S3, model no. GT-i9300.

You now have the option of choosing between the evergreen CyanogenMod 12.1 custom ROM, or the AICP one. Both offer unique set of features that have piqued our interest for long, and both are worth a try, else we’d not be giving them a mention here.

Samsung Galaxy S3 Android 5.1 update

Sr. #

ROM

Downloads

Major Bugs

1

CyanogenMod 12.1

(CM12.1)

Development page | By: u2funker

Credit: JustArchi, moster2, and arter97

» Messenger (fix: install Textra app from play store)

» Camera (fix: install Kamera Zoom FX from play store)

2

Android Ice Cold Project

(AICP)

Development page | By: rap_turkez

None

Supported devices
  • Galaxy S3, model no. GT-I9300
  • Don’t try on GT-I9305 or
  • Don’t try on any other Galaxy S3 set from US of elsewhere with different model no., or any other Android phones
Instructions

Warning: Warranty may be void of your device if you follow the procedures given on this page. You only are responsible for your device. We won’t be liable if any damage occurs to your device and/or its components.

>> Again, do not install this ROM on any other model of Samsung Galaxy S3 than GT-I9300!

Important Note: Backup important files stored on your device before proceeding with the steps below, so that in case something goes wrong you’ll have backup of all your important files.

  1. Transfer the ROM file to your device’s internal storage and remember the location where you save it.
  2. You need TWRP recovery for this. Get it from here. There’s good instructions set there, too. For more help, Google is your friend.
  3. Reboot into recovery mode. (How to: Power off the device and then after 5-6 seconds, press and hold Power+Home+Volume Up till you see Samsung’s logo.)
  4. Make a backup. Once in TWRP recovery, take a backup of your current ROM. Select Backup, then do a “Swipe to Back Up” on the bottom of the screen. Wait for the backup to finish, it’s a time consuming process.
  5. Wipe your device. Once the backup is finished, do this: tap on Wipe, then Advanced wipe, and then select Cache, System, Dalvik/ART cache and Data. Then do the “Swipe to wipe” at bottom to ready the device for ROM flashing by erasing the cache, dalvik cache and data in one shot.
  6. Install ROM now. Go back to the main menu of TWRP recovery and select Install. Navigate to the file where you saved your ROM’s zip file, select it and “Swipe to Confirm Flash” on the bottom of the screen. Now wait until the flashing process finishes.
  7. Also flash the Gapps the same way as ROM.
  8. Go to back to recovery’s Main menu, select Reboot » select System.

Your device will now reboot with Android 5.1 update, thanks to CM12.1 custom ROM.