Default [xP] Damaged Bootloader?

My friend got problem with his Xperia P.
When he turn on device it vibrates and nothing more, but sometimes (around one time for 15 attempts) it turning on and working properly.
Turn off and fun starts again

It was flashed soft with PC Companion, flashtool and via fastboot. Every time the same situation - once works properly, fourteen times any reaction except one viber.

Is there stoned bootloader? Or something else can be?
Help please

Sorry for my language - always got bad grades in grammar