iPhone X only turns on when charging after screen replacement?

My screen developed two vertical green lines. I took it to Apple to see if they would fix it free of charge since it’s a common issue, but they refused and I’m out of warranty. I decided to replace the screen myself. It was working the first day, but I didn’t seat the screen properly so I opened it back up to reseat the screen. This is where the issues started. The phone would not turn on by itself. I connected it to a charger and then it turned on. I took it off the charger and it was fine too, but then the next morning, the phone was dead. I opened it back up and tried to reseat the cables, and still nothing unless I connect it to a charger. I also smell something burning when I do this, so I haven’t tried it again. Now, it’ll only work for a few seconds after disconnecting it from the charger. I’ve tried draining the power by holding down the power button with everything disconnected, but still nothing. Did I fry something? I’m in college and I can’t afford to do much. Any help would be appreciated.