Maybe the bended ribbon cable touches the back of the board. It does get out of its bend form with time because of heat. Try bending it (gently) back into shape and away from the back of the board. If necessary add some space between the screen and the board with some kind of a spacer.
i took it all apart, and tried to play around with the ribbon cable and checked all connections... nothing. i am wondering could it be a fried chip? but the cable is kinda bent. but all the lights work fine. but it just turns off with the backlight.