If the phone is very hot and the screen is off, it is possible it is just overheated and giving it time to cool down could help. The fact that it still shows signs of life and is still hot could possibly mean that the OS got caught in a loop and is partially functioning.
If it is the *battery* that is heating up, that could be dangerous. Could you post a photo of your phone and highlight the spot that is getting hot? If it is over the processor or over the battery could help determine this. [guide|21499]
If the battery is not getting hot, you may find results by just letting it die completely and then trying to charge it again. If it is something like the OS got stuck in a loop a simple restart may fix it (though restarting it without being able to use it means waiting).
If you have the tools, take the back off and disconnect the battery will be your best bet for a faster test.