For those of you who rooted your T-Mobile Galaxy S2 SGH-T989, I HIGHLY advise you to make a backup of your rooted stock ROM just in case something goes wrong.
Here’s how to backup ROM on your T-Mobile Galaxy S2:
Make sure you have an external microSD card inserted on your T-Mobile Galaxy S2 before beginning as backups are only saved to your external microSD.
Step 1. Download ROM Manager off the Market and install.
Step 2. Open up ROM Manager and choose “Flash ClockworkMod Recovery”. This will install the latest version.