Why is my iPhone 13 overheating after battery replacement.

My IPhone 13 shut off unexpectedly on sunday(today is Wednesday) it overheated and shut off. I haven’t but even had it for 2 years. I gave it a couple days, tried plugging it in and leaving it unplugged. Saw somehing that’s said the battery tends to do this on he iPhones 13. So I ordered a new one and replaced it. But once I installed the new battery I wanted to make sure it worked before securing the screen back in place. But once I connected the battery to the circuit, it overheated again, it is really hot where the display and battery cables plug into. It is also really hot where it says A15 Bionic. So I know it’s not the battery. Anyone else have any problems with this? Can someone that knows more tell me what’s and how I can fix it myself (would prefer saving money). Could someone tell me why this is happening and what’s wrong?