Ursprünglicher Beitrag von: Reece ,
Have you opened the device to check? I talk from past experiences with 5/6 screens, but where the backlight on the back of the screen is soldered, there should be a bit of electrical tape, to prevent it shorting. I know on 3rd party screens, sometimes they leave this tape missing and it can short, stopping the backlight from working. Open and check it out, could even be a case where the customer has liquid damaged it. I would say there is a good chance it is the above though, and obviously try the usual resets.