- Download and install the latest Flashtool version on your PC
- Download the desired firmware (.ftf) and put it in the /flashtool/firmware folder
- Open FlashTool and click Flash
- Follow the on-screen instructions: turn off the phone, press and hold the BACK key and plug it on the PC
- Wait and... done (usually takes no more than a minute)!
- Download Busybox from the Android Market, open it and click install
- Download xRecovery, open it and click install (the three icons must become green)
- Reboot your phone and repeatedly press the BACK key when the SE logo pops up
- A blue screen will show up. Navigate through menus with the volume keys, the HOME key and the BACK key
- To backup your current rom, go to Backup Restore and choose Backup
- To install a custom rom, go to Install Custom Zip From SD Card and pick the rom's zip file
- Reboot phone and... done!