Sadly the panel its self has likely failed and will need to be replaced. Unlike a LCD panel which has a light source behind it OLED panels emit their own colored light per pixel. Here we have a matrix of lines that run across the panel to supply the signal and needed power for the panel to light up. A good bang or liquid spill can kill the panel. Here’s the guide [guide|142499] besides getting a new panel as the cheaper option you might just want to get a new uppercase if your battery is also close to the end of its life as that’s less work and frankly quicker!