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Flash AvatarROM Jelly Bean 4.2.2 custom OS for T-Mobile Samsung Galaxy S3 T999

The T-Mobile variant of the Galaxy S3 can be updated to Android 4.2.2 Jelly Bean using a custom ROM such as AvatarROM. Use this guide and you’ll learn how to successfully flash the new custom OS for your device in under 10 minutes.

The Avatar ROM uses features and functions from CyanogenMod 10.1 Release Candidate 5, AOSP Android 4.2.2 JB, MIUI ROMs and from the stock Samsung TouchWiz UI. It borrows the status bar from CM 10.1, it packs a theme chooser for both CM and MIUI themes, Bazooka Launcher, dockbar added, messaging app, boot animation, themeable emoticons, font theming, OTA updating tool, multiple lock screen features, weebo etc.

There are tons of other features and functions that will be installed along with the AvatarROM. More info about this custom Jelly Bean operating system can be found at the XDA thread here.

In order to make sure that you successfully flash all the required files, you will need to take a look at the guidelines below. Here’s what you need to know:

  • use this tutorial only with the T-Mobile model of the Samsung Galaxy S3. Your device has the T999 model number.
  • don’t try to use the files you find here with any other Galaxy S3 variant, as you will end up bricking it.
  • your phone has to be rooted and running a custom Recovery image like TWRP or CWM.
  • I have used the CWM Recovery mode for this tutorial, but the TWRP one will work just as well. If you’re going to use TWRP, then you should make sure to correctly apply all the actions using the corresponding buttons. If you’re having problems, tell us in comments.
  • create a full NANDROID backup for the ROM that is currently installed on your smartphone. This will act as a restore point for your device and it can be used in case your device doesn’t boot with the new OS or you simply don’t like the AvatarROM.
  • in the ‘how-to’ guide you will find a step that will tell you to wipe data and factory reset your phone. This means that you will lose the data from the ‘system’ partition, which is why you will lose SMS, Call Logs, installed applications and other similar data. Without applying the ‘factory reset’ step, you won’t be able to complete the installation of the new OS.
  • use the following tools to backup SMS, APN Internet Settings and Call Logs info: SMS backup & restore | Call Logs backup & restore | APN Settings Backup & Restore. Root access is required for some of these apps.
  • if you’re planning on backing up applications, then you should search for such tools using Google Play Store.
  • enable the USB Debugging option from your phone’s Developer Options, under Settings.
  • If Developer Options menu isn’t shown, then you will have to enable it by opening Settings, then About Device. Scroll down and tap 7 times the Build Number section to enabled Android developer settings.
  • make sure that the phone’s battery has at least 50% power left in it before completely discharging.
  • this is a tutorial for advanced users, you cannot blame us in case something goes wrong and the phone gets bricked or you lose any important data in the process.
  • read the entire post and don’t skip any instructions that I have listed below.

Now that you know all that, continue to the next part of this article. If you cannot complete the installation, then you should ask for more help in comments, make sure to leave a detailed comment so that we will be able to find a viable solution for any problems that you might encounter in your quest to flash a custom Android 4.2.2 JB ROM for your smartphone.

How to flash AvatarROM Android 4.2.2 Jelly Bean custom ROM for T-Mobile Galaxy S3 T999:

  1. Download the Avatar ROM zip file from HERE.
    > save the file on your computer and don’t unzip.
  2. Download Gapps for custom Android 4.2.2 ROMs from HERE.
    > don’t unzip.
  3. Connect the phone with your PC and then copy both files onto your smartphone’s internal SDcard.
  4. When the files are copied, then you can disconnect the device from your PC. Power off the TMO Galaxy S3 now.
  5. Boot the phone into CWM / TWRP Recovery mode.
    > I’ve used the CWM Recovery for this guide, but you should be able to complete the tutorial with TWRP. Make sure to correctly apply the corresponding actions.
  6. Select ‘backup and restore’ option from the main Recovery screen. Create a NANDROID Backup of the current ROM before installing the new one.
  7. Select ‘wipe data/ factory reset’ and confirm.
  8. Get back to the main custom Recovery screen and select ‘install zip from sdcard’.
  9. Then, select ‘choose zip from sdcard’ and find the AvatarROM zip file. Confirm that you want to install it.
  10. After the ROM is installed, select again ‘choose zip from sdcard’. Find the Gapps file and complete the installation.
  11. When both files have been successfully flashed on your T Mobile Galaxy S3, then you can return to first Recovery menu and select ‘reboot system now’.
  12. Wait for the first boot process to complete and in under 5 minutes you will be taken to the AvatarROM Jelly Bean 4.2.2 main screen.
  13. Enter your Google Account details and take control over your phone once again.
  14. Test all the new functions and then tell us in comments how’s your T_Mobile Galaxy S3 working with the new custom ROM.

If you have any problems during the installation, then you should ask for more help in comments. If you didn’t manage to install AvatarROM at the first attempt, then you should retry after you remove the phone’s battery. Re-insert the battery and then flash once again the new ROM using the tutorial.

Make sure that you apply all the steps listed above including the ‘wipe data/ factory reset’ step, as that might be why your phone doesn’t want to boot with the new AvatarROM build.

If you don’t like the new custom Jelly Bean 4.2.2 ROM, then you can easily restore the previously installed one using the backup file created at step 6. These were all the instructions that I had for you. I hope that your T-Mobile Galaxy S3 works great with the new custom ROM.