iPhone overheating after housing replacement

Hi there. My iPhone 5s housing wasn't in a good condition so I decided to replace it. Before the housing replacement my phone didn't get hot but now after the housing replacement my phone gets really hot. Particularly from the motherboard. What could be the solution to this?

Also,the front camera has stopped working. I have checked the flex and all seems fine as the proximity sensor and earpiece speaker work fine just the camera doesn't seem to work now. I have ordered a replacement but could the overheating be due to the front camera not working?

Thank you for you're time.