Overheating!

Hey all,

it started overheating after using carplay for a while and now it just drains battery and is always overheating even when unplugged and just in my pocket, it's become unusable. I've tried replacing the battery but that didn't change anything. Does anyone have any ideas why this could be happening and how I could fix it? I can't afford to buy a new phone right now so I kind of need this to work