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
![Shocked :o](https://nikongear.net/revival/Smileys/default/shocked.gif)
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.