i don't know about cameras or anything super complicated, but in automotive if something is heating up like that then the wiring has a problem. probably a short or ground was not setup properly, old wires, happens sometimes on the ignition part of some older toyotas and drain your batteries

might be useless information but the camera might be trying to say something.
the only thing that I am aware of that actually heats the camera is long exposure and liveview/video.