I have the xperia arc s, and recently ive had a problem where when i switch my phone on, the backlight comes on, but the screen stays blank, i have to wait 5 mins for the screen to fix, i can feel the phone vibrate when i touch it so its like the phones still on, but the screen stays blank? now i have the problem where ive waited half an hour and its not come back on? what shall i do?