This is my first post,
I had the same problem, tried upgrading to 2.3.5 GingerXperia & got bricked, i.e. stuck at booting of my W8, got the solution after extensive search on line, downloaded FlashTool_0.2.9.1 and downloaded Firmware as given in
Google: Recovering Dead/Bricked phone.
flashed the cell by following the instructions
2.Flash this ftf file using Flash Tool.
[ Detailed post on how to flash ftf files.
3.Root phone using SuperOneClick.
4.Install Xrecovery. - View Post.
5.Restore your original backup image.
similarly same tool can be used to flash & change the base band, now I can install gingerbread all versions in a "Flash" btw I have tried all the versions upto V19 & each has some problem or the other, most give problem with blue tooth audio playback on my car receiver, finally GingerXperia V14 was the perfect one. works great, neat settings.