Screen will not light up

I have a j7 prime that my son broke the screen on. I bought a new one and replaced it, and at first I thought it was broken, and ordered a new one. After installing the new one I discovered both screens displayed just fine, but they don’t light up at all, and the only way to see what is displayed on the screen is to use a flash light or lamp. I have tried restarting it, factory restarting, restarting in recovery mode, and all of the other tips you guys said to try, to no avail. I also tried updating the system, with no luck. It is obviously a problem with the phone in some way, because I tried 2 different screens and it happened the same with both of them. If I have the phone outside during the daylight, I can use the phone without much of a problem. Please help, I’m at my wits end! This is frustrating the crap out of me, and I don’t know what to do!