T-Mobile Samsung Galaxy S3 Gets Android 4.1.2 Jelly Bean Via SynergyROM (How To)

T-Mobile users who own the Samsung Galaxy S3 can update their smartphones to Android 4.1.2 Jelly Bean via the SynergyROM, which brings several improvements and new features.

With the aid of SynergyROM Android 4.1.2 Jelly Bean firmware, T-Mobile Galaxy S3 users will get a number of features like 4-in-1 reboot menu, rotating homescreens, fully Deodexed, Zipaligned, Busybox, Superuser, Debloated and Multi-Window with free-floating windows.

What's more, it will bring multi-carrier support for any Galaxy S3 offered by carrier's Verizon, Sprint, AT&T and T-Mobile — all in one ROM. Here's a step-by-step guide on how to install the ROM for your Galaxy S3. 


- Remember that the instructions are applicable only for use with the T-Mobile Galaxy S3 SGH-T999. Flashing the ROM on any other device may brick your smartphone. Verify the device's model number by navigating to Settings > About Phone.

- Remember to read through the instructions before beginning.

- Remember to back up important data.

- Ensure your phone's battery power is at least 85 percent, if not fully charged, to avoid disruption due to power loss.

- Users should note that the instructions given in this guide are meant for reference purpose only and do not cover any warranty claims involving device damage or issues arising out of installing the firmware on your Galaxy S3. Users are advised to proceed at their own risk. iTechPost takes no responsibility for any damage or issues you may encounter with your smartphone, including bricking your device


- Ensure that you have installed the USB drivers for the Galaxy S3 SGH-T999 on your PC properly.

- Enable USB debugging mode on your phone.

- Ensure that your phone is rooted with ClockWorkMod (CWM) installed on it.

Files Required 

- Download SynergyROM Android 4.1.2 ROM.

- Download Google Apps.


Step 1: Connect your Galaxy S3 to the PC using the USB cable.

Step 2: Next, mount the storage and copy the downloaded SynergyROM Android 4.1.2 to your phone. Do not extract any files.

Step 3: Next, turn off your phone and disconnect it from the USB cable.

Step 4: Switch on your Galaxy S3 SGH-T999 while pressing and holding the Volume Up, Home and Power buttons together until the device boots into Recovery mode.

Step 5: Next, in the Recovery mode perform a backup of the existing ROM. Do this so that you can restore later in the event that the new ROM doesn't work.

Step 6: Select "Backup and Restore" and select "backup" again on the next screen. Return to the main recovery menu once the backup is through.

Step 7: Perform data wiping to avoid any conflict between this ROM and the older one. To do this follow these steps:

- Select "Wipe data/factory reset."

- Next, select "Yes" to confirm.

- Wait till the data wiping is complete. Once the wiping cache partition process is through, select "Wipe Dalvik Cache" under "Advanced" option. Go back to the recovery menu once complete.

Step 8: Next, scroll down to "install zip from SD card" and press the Power button to select the same. Select "choose zip from SD card" and select CM10.1 M3 Android 4.2.2 ROM using the power button.

Step 9:  Select Yes > Install. The procedure should start now.

NOTE: Repeat steps 8 and 9 for the Google Apps zip file.

Step 10: Once the installation is finished, select "Go Back" and reboot the phone by selecting "reboot system now" from the recovery menu. Your Galaxy S3 will boot now and can take about 5 minutes, so wait until the process is done.

You now have the SynergyROM Android 4.1.2 Jelly Bean installed on your T-Mobile Samsung Galaxy S3. You can check the firmware version by going to Settings > About Phone.

© 2021 iTech Post All rights reserved. Do not reproduce without permission.

More from iTechPost