Here's the thing though, it stopped working for a reason. Unlike the black box that I find so many people treat electronics like that they do not understand, don't just blame the FET for failing. Something caused it to fail. Either wiring, or a bad motor, jammed impeller, something causing likely high current draw.
You might be at that point where having a tech look at it, properly fix the problem, repair your old board or get a new one, likely replace the fan motor out of caution to protect the new board might be the right answer.
I just would hate to see you buy a board, slap it in, and then smoke it in the first 30 seconds of powerup. Then you both paid for a board, and still had to send off for repair.
