Xperia Sola keeps rebooting after reset
Does the phone fully boot or does it reboot almost immediately?  I have had similar experiences with phones (from other vendors) not being recognized until some time after they have booted (mostly likely services need to start etc. etc.). I love (not) how this happens just at the time when you need to repair your phone!

Have you tried removing SIM cards, extra storage etc.  Sometimes if you can get the device to boot differently it will get far enough along to be "recognized".