ICS Installation Procedures for XPU:
Official:
1. Backup all data, all media and contacts. If you are rooted, backup user app +app data using titanium backup, or else you can reinstall the apps later from Google Play>My App Library. Refer to: http://talk.sonymobile.com/thread/36355
2. Do a factory reset and wipe all data on the internal memory.
3. Use Sony Update Service to upgrade. For stable upgrading procedure refer to: http://talk.sonymobile.com/thread/47105
4. Repair using Sony Update Service.
5. Do a factory reset and wipe all data on the internal memory.
6. Remove the live wallpaper and follow some basic RAM and battery saving procedures. Refer: http://talk.sonymobile.com/thread/44278
Unofficial (may void warranty):
1. Backup all data, all media and contacts. If you are rooted, backup user app +app data using titanium backup, or else you can reinstall the apps later from Google Play>My App Library. Refer to: http://talk.sonymobile.com/thread/36355
2. Do a factory reset and wipe all data on the internal memory.
3. Download the .ftf file from XDA corresponding to your model.
ST25i: http://forum.xda-developers.com/showthread.php?t=1918920
ST25a: http://forum.xda-developers.com/showthread.php?t=1916419
4. Download Flashtools.
androxyde.github.com/index.html?1349344649000
5. Use flashtools to flash the .ftf file. Exclude baseband if you are unsure of the baseband of the .ftf file. Refer: http://talk.sonymobile.com/thread/35239
6. Repair using Sony Update Service.
7. Do a factory reset and wipe all data on the internal memory.
8. Remove the live wallpaper and follow some basic RAM and battery saving procedures. Refer: http://talk.sonymobile.com/thread/44278
If there are any lags or glitches even after this, do a settings reset and replace the live wallpaper with a normal one. Please do everything carefully and responsibly.
