I have a GMP125-4 unit, the air quit working on it. Before it quit, it tripped a breaker. Flipped the breaker back it worked for about 5 minutes then quit blowing again. Took the door off, held in the black switch to act like the door was still on there to see if the light on the circuit board was on, it was not. What else can I do to see what the problem is and fix this?

Check the fuse on the control board.

You will have to use a meter to find out if you have control power and find out if you have a short and where it is.