I also have the same tyoe of problem. Few months ago i droped my phone and then my screen cracked up i was using it anyway. Few weeks ago i got my screen changed but the same thing is happening to my screen again. While using the phone suddenly coloured line appeared on the screen and then it goes blacked out. When press the upper corner of the phone it gets started again but its not a permanent solution. What do i do now.. (Btw sorry for my bad english