really? asking this question in an Xperia S forum?
do a back up with a clean ROM - no add-on apps installed - like after a fresh reinstall. delete any left over folders as well on SD card (except of course for the CWM folder)..
before doing a fresh reinstall from back-up, do a hard reset - phone ...
arrrgg i hate t-mobile!
well.. there was a way to open it, via s1 server with SEtool software.
but now the s1 server is down, for unknown time.. unlucky you.