<--Google Page ads-->

Update T-Mobile Samsung Galaxy S3 T999 to Official CM10-M2 Android 4.1.2 custom ROM

The latest CM10 Monthly update has been released for Galaxy S3 T-Mobile variant and it is based on the Android 4.1.2 Jelly Bean ROM. Use the instructions that I have listed in this post and you will manage to successfully update your device with the latest ‘stable’ CM10 build.

It brings several tweaks and improvements that should make your device run even faster. Bugs and errors present in earlier release have been fix and you shouldn’t find any major bugs in this new one. However, this is still an ‘in-development’ release and it might pack some errors, which is why you should tell us in comments if you find such bugs.

Before starting to flash this update, you will first need to read the preparation info listed a few lines below, as you will learn how to properly configure your Galaxy S3 phone. You will learn what steps to take and apps to use in order to backup your most important files.

I think that these are all the general instructions that you had to read and now you should move to the next part and prepare your Galaxy S3 T-Mobile model number T999 for the installation of CyanogenMod 10 M2 Jelly Bean custom ROM:

  • Check the phone version by opening ‘Settings’ app and then open the ‘About device’ menu. If the T999 model number is listed then your phone is indeed the T-Mobile US Galaxy S3. Do not attempt to flash the files you find here on any other Android smartphones.
  • Your phone should have CWM Recovery installed and it should also have root access. Without these you will not manage to flash the CM10 custom ROM.
  • You can save a list of installed apps, the SMS, Call Logs and the APN Internet Settings using these apps: SMS backup & restore | Call Logs backup & restore | APN Settings Backup & Restore | AppBack for Android. Note that some of these will not work on devices without root access.
  • Create a full ROM backup of the existing Android OS so that you will be prepared in case something goes wrong and you cannot use your device after the CM10-M2 ROM installation. Also, you can restore the backup in case you don’t like this new custom ROM.
  • Use this guide here to learn how to sync your Contacts with your Gmail.
  • USB Debugging option should be activated.
  • The CM10 M2 Jelly Bean is an official release by CyanogenMod team and not an official Samsung firmware update.
  • Note that we won’t be held responsible in case your device is bricked in the process. Also, we cannot be blamed if you lose any important data files.

These are all the preparation instructions that you had to view before starting to update your device. Make sure that you apply all the steps listed below.

How to install CM10-M2 Android 4.1.2 custom ROM on T-Mobile Galaxy S3 T999:

  1. Download CM10 Jelly Bean ROM zip from HERE. Make sure you download the latest version and save it on your computer’s desktop screen.
  2. Download the Gapps for Jelly Bean zip from HERE. Make sure you download the file for Jelly Bean and not some other versions.
  3. Connect your phone to your PC using the USB cable. Move both files on your device’s internal SD card. and after that you should disconnect the phone from PC. Power off the T-Mobile Galaxy S3.
  4. Boot into CWM recovery mode by pressing at the same time these buttons: volume up, home + power. When the screen powers ON you should release the buttons.
  5. First thing that you should select is ‘wipe data/ factory reset’ from the main CWM Recovery menu. If your device is already running a CM10 based ROM then you can skip this step and only apply the ‘wipe cache’ and ‘wipe dalvik cache’ options. However, we recommend you to wipe data and factory reset the device so that you won’t have any problems with the new CM10 release.
  6. After you applied the wipe data, you should select ‘install zip from sdcard’. From the new menu select ‘choose zip from sdcard’ and after that browse your device for the CM10 M2 zip and confirm its installation.
  7. When the ROM is successfully installed you should select once again the ‘choose zip from sdcard’ option and then browse for the ‘Gapps’ zip. Install it.
  8. After the CM10-M2 and Google Apps zips were successfully installed you should return to the main recovery menu. Select ‘reboot system now’.
  9. The Galaxy S3 T-Mobile will now restart and this first boot process with the new ROM shouldn’t take more than 5 minutes.
  10. When the boot is complete, you will see the Jelly Bean CM10 home screen. Enter your Google Account credentials and take control over your phone.

That should do it, now your device has been successfully updated with the latest CyanogenMod 10 custom ROM.

If the first boot process takes too long to complete, the you should power off the device completely and remove its battery. Re-insert the battery back in its place and then repeat the entire tutorial starting with step 4. You should be able to flash the custom ROM on your seconds attempt.

In case you encounter any other problems, then you should ask for more help in our comments field.