I didn’t see you mention removing the motherboard. That was your mistake. Rear glass removal requires removing the motherboard, camera etc just to be on the safe side. It takes a lot of heat to get that glass off. Too much heat on this motherboard can cause problems. You will have to take it or send it to a micro solder tech to have it tested out and figure out the problem. Could also be something as simple as the battery got damage or the housing creating some sort of short but either way you need working parts to test those possibilities.