Replaced battery - screen completely stopped working

Had someone I thought I could trust fix the broken glass on the back, he didn't have the right model and only noticed until the very end. While we waited for the right one to be delivered, he admitted to piercing the battery and that it should be replaced.

Next day, the phone would shut off every once in a while, but would work fine after a charge (battery would just die randomly)
Went to charge it as normal, apple logo would come on and then it would shut off and it would repeat that cycle. I decided to disconnect the phone and not charge it or attempt to turn it on until the battery was replaced.

Battery was replaced (not by the same person)

When we went to turn on the phone, you just get a messed-up screen, bunch of lines and colors, nothing is legible. Everything is connected properly.

Going to buy a screen replacement now but wanted some insight. When we removed the battery, it was completely beat up, looked like someone shot at it. Could the bad battery had messed up something in the display? Am I completely fried?

Thanks for reading!