Why is my phone shutting down due to overheating

[Android Central Question]

I have an LG K20 Plus with a broken screen. I replaced the entire display. When I originally turned it on, it worked fine for a few days. I had forgot to hook up the speaker so I took it apart to do that. When I went to turn it back on a warning came up saying my phone is overheating and shutting down for my safety. I'm getting this message the second my phone turns on. I can't adjust any settings or look for any programs running. I can't do anything to recover data either as the phone shuts off immediately after it starts. I've tried safe mode. I've factory reset the phone. I've got a new battery and nothing works. Although I was very careful, I don't know if I did something to the motherboard. I did try to put a screw into what I thought was a screw hole. It wasn't and it did leave a small indent on the motherboard but it doesn't appear that it penetrated it at all. Also, when I first turned it on it said something about not being able to mount my SD card. Not sure if that is related. Anyway, I'm stuck and I don't know what to do. Google hasn't been much help as all their advice are for phones that are actually overheating. Thank you for your time.

 

[B. Diddy]

Welcome to Android Central! I realize this isn't very helpful, but since it'll be very difficult for anyone here to know exactly what you might have done wrong in the repair process, it'll also be very difficult to offer any solution. It'd be best to bring it to a qualified repair shop.

 

[MexicanKutie]

Thank you for your advice and for taking the time to respond. Have a great day!