I've posted this in some other threads but I keep seeing people asking about it so I'm posting its own thread. You do not need to be rooted to do this. This is for the T-Mobile Galaxy S2 SGH-T989 phone ONLY. Please see this guide for more instructions. If you're running ICS and want to go back to Gingerbread: Make sure on your phone USB Debugging is checked in Settings > Developer Options Make a folder on your PC to put these files. Odin 1.85 - Make a sub folder and extract Odin in it. download this file. It is the updated stock UVLDE rom. Extract it in your folder. You should already have Samsung USB drivers on your PC. If you don't, download and install Kies. It comes with the latest drivers. 1 - Launch Odin by double clicking the Odin3 v1.85 file. Plug your USB cable to your computer but not your phone. 2 - Power off your phone. Then hold down both volume buttons and plug the USB cable into your phone. Press the volume up button when you see this menu. You will then go to the download screen. 3 - Wait for the Com port in Odin to turn yellow as in the pic. You do not need to check anything that isn't already. Just be sure that Re-Partition is NOT checked. It shouldn't be. 4 - Select PDA in Odin and browse to the stock UVLDE file you downloaded and extracted. Select it. Now press Start and Odin will flash the stock rom. When it is finished you will see a green PASS in the top section. 5 - Odin should reboot your phone. You should now be in the stock updated Gingerbread ROM. When you reboot you may have force closes in processes. Don't Panic. This is normal. Follow the steps below. Power off your phone again. Hold both volume buttons and the power button at the same time. When the phone vibrates, let go of the power button but keep holding both volume buttons. In a few seconds you should be in the recovery menu. Use volume buttons to move up/down and power button to select. *if power button doesn't work, use your home key*. Go to wipe data/factory reset and select it and then select yes. Next, select format cache partition and next select yes. Now select reboot. You can also go from Gingerbread to ICS using the same method. Just use the stock ICS file instead of the Gingerbread file. Download it from one of the links at the top of this thread.