I hope someone can help!!

I've got a w810i, when I start it up it goes to the start up screen, stays there for a while and then flashes white a few times and switches off.

Also, when connecting it to the computer via usb, everything works perfectly like a normal phone would - so i know it is not the screen.

i've tried flashing it full - main + fs + cda - but still the problem remains.

I hope someone can help :(

regards,