How to Flash Custom ROM onto the Samsung Galaxy S2 (T-Mobile) 10 by Alexander Maxham on October 26, 2011 1:28 am 2 Finally, T-Mobile Galaxy S II users can get a custom ROM built for their phone. Last week I wrote about how to root your T-Mobile Galaxy S2, and now here is your first Gingerbread custom ROM. Disclaimer: Please follow this guide at your own risk. Android Authority will not be liable if your device gets damaged or bricked during the process. The first step is to make sure that you have root on your phone along with ClockworkMod Recovery. Now download the ROM zip file from here and save it on your desktop for ease of access. Once done, connect your phone to the computer, mount SD Card as flash drive and copy the downloaded zip file to SD card root. After you are done copying the ROM file to SD card, reboot your phone in ClockworkMod Recovery. You can use ROM Manager’s in-app option to boot into recovery. After you are in recovery, make a Nandroid backup of your current ROM using on-screen options. Once you are done making the backup, Wipe Cache Partition and Factory / Data reset your phone. Once done, navigate to install zip from SD card and install the ROM zip file. Once the installation is complete, reboot your phone. That wasn’t hard, was it? You now have the first custom ROM on your T-Mobile Samsung Galaxy S2. In case you have any issues or need to discuss more with the ROM developer, please head to the official XDA thread posted here.