Screen black after replacement, old screen doing the same thing.

I replaced a screen on an iPhone 6 with a new screen. As soon as I plugged in the new screen, the phone buzzed. When I went to test the new screen, the screen would not turn on. I replugged in the old screen and it would not turn on either.

The phone works fine and still buzzes when hooked up to a charger or a computer. I've tried the following with no luck:

-Unplugging the battery for awhile.

-Verified that all connectors are clean and no prongs are bent.

I've been replacing screen for a long time and have never come across an issue like this before.