Chosen Solution
My screen goes black when using. Locking and unlocking the screen turns it back to normal. If i drop the phone from like 1-2 inch on my desk the screen slowly turns black. Tried changing battery and screen once.
If you have ruled out a screen problem the next thing you need to determine is it the backlight or image. When it goes black shine a torch on the screen and see if there is an image displayed. If there is it would point to a backlight problem probably a small filter that is not making contact properly. If there is backlight but no image I would be looking for long screw damage.
