Sounds like the liquid indicator in the headphone jack turned color and thus indicates liquid damage.. See:
- Also try DFU mode after try recovery mode
- If not successful and you can't fully turn the iOS device fully off, let the battery fully drain. After charging for an least an hour try the above again.
- Try on another computer
- If still not successful that usually indicates a hardware problem and an appointment at the Genius Bar of an Apple store is in order. The hotness indicates hardware damage
If liquid damage
Apple will exchange your iPod for a refurbished one for $99 fi a 16 GN one and $149 for the other 5G iPods. They do not fix yours.