I have an Arduino Nano and when I power it either via USB or VIN it heats up very quickly. Before it started to overheat I heard a spark but didn't see which pin sparked and I think that's the problem. During the spark I had a L293N motor drivers one IN pin was connected to the board. I tried uploading the blink sketch and disconnecting everything but still having the same problem. I can't see any visual issues on the board. How may I fix it?