My phone got problem while using it's screen light turn off, i've checked in bright light and in sunny day phone's screen is working fine but only light of screen go off. but if it's auto light off time is passed and then again any key is pressed it's screen lights are on again, but randomly it turns off, mostly pressing D pad and 123456 key pad numbers it's light turn off. I've master reset, updated using SEUS but problem still remain. there is no problem with it's calling and answering problem.