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Settings > accessibility
you might have to pull down the notification bar with 2 fingers. if what you are saying is that the test fail at the top of the screen then you will have to contact yoru local Xperia Care
You could also do a system repair with pc companion.
That's a good idea
Bridge (for Mac)
Alternatives on How to backup Xperias
http://talk.sonymobile.com/thread/36355