I literally just had the same problem!!!! I came here specifically to figure it out. Were you trying to update it and the update failed? Because that is what happened to me, this is what helped me to fix it
So what I did was open the sony ericsson pc companion, pressed the power button, then plugged it into the usb, then itll say there was a problem connecting and itll give you an option to repair, it says itll erase all the data on your phone, not memory card, so I removed my sim card just in case, it updated to 2.3.4 no problem turned on fine but took a minute or so, saw that it was in spanish, turned it off, put sim card in, sends you through the start up process again, although a little different and specifically for the American version which I didnt get before, and it should be the way you left it, at least it was for me
Here is the link again if the first one didnt attach
http://www.sonyericsson.com/cws/support/mobilephones/learn-more/subject/softwareupdatefailed/xperiaa...
