Install CM 10.1 M1-build Android 4.2.1 Jelly Bean on T-Mobile Galaxy S3 T999

Jan 29, 2013

The CyanogenMod team has released a monthly stable version of CM 10.1 for a variety of US version Galaxy S3 smartphones. This build supports T-Mobile Galaxy S3 T999. The latest M1-build is based on Android 4.2.1 Jelly Bean ROM, it will allow you to enjoy the latest iteration of Android 4.2.1 Jelly Bean your T-Mobile Galaxy S3 T999.

Before installing this ROM, it is pertinent to mention that ROM flashing can cause your phone to brick. Although most of the ROMs today are virtually brick proof, but it is always recommended to be cautious since it will be your own responsibility if anything goes wrong.


  1. CM 10.1 M1-Build 4.2.1 Jelly Bean ROM For T-Mobile Galaxy S3 T999 [File:]
  2. Google Apps [File:]

Guide to Update T-Mobile Galaxy S3 T999 to CM 10.1 M1-Build Android 4.2.1 Jelly Bean

  1. Connect your phone to PC using USB cable.
  2. Copy downloaded files to the SD card of your phone. Important: Don’t extract any files.
  3. Disconnect USB and then turn off your phone.
  4. Boot into recovery mode. To do so, press and hold Volume Up, Home and the Power button, continue to hold all three until the screen flashes, then release all buttons.
  5. Perform a Nandroid backup of your existing ROM, so that you can recover your current install if the new ROM does not perform satisfactorily for you. To perform a backup, select Backup and Restore, then on the next screen, select Backup again. Go back to main recovery menu after backup is complete.
  6. Now, select wipe data/factory reset, select ‘Yes’ on next screen to confirm your action. Wait few minutes till the data wipe is complete. Now come back to CWM recovery main menu. Select wipe cache partition and after wiping process done, select Wipe Dalvik Cache under advance option to perform Dalvik cache wiping.
  7. Select install zip from sdcard, then select choose zip from sdcard. Now, locate the file that you copied earlier in Step 2 and select it by pressing Power button. Confirm installation by selecting Yes. Install the said zip file on the next screen. The ROM installation will begin.
  8. Once the ROM installation process end, repeat the step 7 but choose the file instead of ROM zip to install the Google apps package.
  9. When installation is completed, go back to the main recovery menu and select reboot system now to reboot the phone and boot up into customized Android 4.2.1 Jelly Bean ROM CM 10.1 M1-build. The first boot will take time, so be patient!

You are now running CM 10.1 M1-build Android 4.2.1 Jelly Bean ROM on Galaxy S3 T999. If you are facing any issues, feel free to mention it in our comments section.