Pin no 21 on my Teensy 4.0 automatically got internally shorted with ground. So now irrespective of anything I program, the pin no 21 remains shorted internally. I have inspected the board and there is no external short for sure. There was an instance where I declared that pin as an output pin and gave it a 3.3v input this was via a resistor so there is no case of short circuit. What might have caused it to get shorted permanently with ground internally..? Other pins are working perfectly fine.