backlight is on but No Image but phone works

I originally bought this iPhone with water damage saying that the screen won't turn on but phone works. I replaced the screen and the phone turned on and worked with iamge. But, recently, I had to replace the screen on the phone. When I tried to turn on the phone, the phone looked as if the screen turned on but the phone displayed nothing on the screen. Just the backlight. When I looked at the phone again, the connector for the second left one had a black mark on the 4th pin from the right(top). I was wondering if this is either from a Fuse burnt or if the phone has the backlight filter damage. I am not sure and I want some insight on this damage.