I'm having the same problem..
The phone vibrates as normal when I press the power button.
After a few secs it shows the Sony Ericsson text.
And then nothing
I tried a couple of button combo's while starting the phone but its always the same end result, it being stuck on "Sony Ericsson".
It does blink the green LED ones when I hold the Volume Down and Back key with the power button, but then its stuck again..
I did not do anything with flashing, or even rooting.. I just tried to reboot it, cause Maps was acting weird and it hasn't started since.
Does anyone have any suggestions?
Im on Andoid 2.3.3.