Sometimes you recover from a weird situation by pushing the erase button for 3 seconds, then push the reset button for 3 seconds, then select the proper COM port, and upload (hopefully succesfully).
The USB cable is sometimes faulty too. And finally unplug and plug again the USB cable in your PC until you can see the proper COM port.
There should not be overheating of the voltage regulator, in the contrary, ask a refund to your reseller.