@whomrnobody heat=shortcircuit. It is possible that this is related to a bad battery (if nothing has happened to the phone before). Replace the battery and then re-evaluate. If there was any water damage to this phone at any time, or any other major event with it, then it is possibly a motherboard situation. [guide|150564]
Now, there have been instances where overheating was caused by bad firmware. Make sure that your Samsung software is updated and that you are on the latest version of the software.