SynergyROM, a new custom ROM for Galaxy S3 T-Mobile models, is based on Android 4.1.2. Fully optimized and providing excellent performance, SynergyROM is going to make into your list offavourites. Some of the features of this custom ROM for Galaxy S3 include: Jelly Bean 4.1.2, 23 notification toggles, 4-in-1 reboot menu, fully rotating homescreen, custom boot animation support, multi-carrier support (Verizon, AT&T, Sprint, T-Mobile - all in one), fully working PDroid support, multi-window with free-floating windows (exclusive feature), and much much more.

Follow the prereqsbefore you update Galaxy S3 SGH-T999 to Android 4.1.2 Jelly Been SynergyROM:

Create a backup of all important data in yourGalaxy device.Download and install USB drivers for Galaxy S3 in your computer.Enable USB debugging option by pressingMenu>Settings>Applications. Navigate and tap onDeveloper Optionsto ensure thatUSB Debuggingis enabled.Make sure that ClockworkMod recovery is installed.Ensure that your Samsung Galaxy S3 carries more than 70% of charge.

Guide to update Galaxy S3 SGH-T999 to Android 4.1.2 Jelly Been SynergyROM:

Files required:SynergyROM Android 4.1.2 ROMfor Samsung Galaxy S3.

Connect Galaxy S3 T999 to your computer using USB cable and copy the downloaded file to the SD card of your device.Disconnect the cable and switch off your SGS3 T999. Boot into recovery mode by pressing and holdingVolume Up, Downand thePowerbuttons simultaneously. UseVolumekeys to navigate andPowerbutton to select.Now perform a Nandroid backup of your existing ROM to be restored laterif this new ROM does not work or you want to move back: Backup and Restore>Backup. Go to recovery menu after backup process is done.Next, perform a full data wipe operation by going towipe data/factory reset>Yespath. Come back to the CMW recovery main menu and selectwipe cache partition.When done, tap onAdvance>wipe Dalvik Cacheto wipe Dalvik cache data too.After the wiping operation, selectinstall zip from sdcardandchoosezip from sdcard. Locate the ROMfirmware file from SdCard. Tap onyesto confirm installation and wait for the ROM installation process to finish.Navigate to+++++Go Back+++++and selectreboot system now.Wait for the SGS3 to boot in to the new SynergyROM based on Android 4.1.2 for T-Mobile T999 models.