Xperia T suddenly won't turn on ( or charge ) topic

Well Today I last remember I installed a theme. And maybe went on fb
After a hour or two after my phone was like dead
I won't turn on. Can't charge ( no vibration , led )
If I hold it even for a minute it won't turn on !
I tried to connect to flashtool
but my debugging is off.
I can't flash a ftf , nothing
:confused::crying:

And if it can be fixed somehow on a service how much would the repair cost