Phone turns on, but nothing shows on screen

So let me explain the title. I have an iPhone 7 plus that had a bad screen when I got it. I replaced it with a cheap screen off amazon, and it worked for the first part, until I fully put it into the device. After that, the screen stopped showing. The home button would still work (doesnt when phone is off). I tried a new screen but the same stuff happens. It is recognized in iTunes, but it gets stuck because i need to trust the computer from the phone (and I cant). Any ideas on how to fix this issue?