I shorted my 3 in 1 board when I used too long of screw for the tail motor. I was able to repair the board by replacing the 8 pin dual n channel mosfet that is on the opposite side with the gyro.

Then after replacing that I found the small surface mount npn transistor next to the fet was shorted. I didn't have that so I used a to-20 case npn transistor pulled off of the board by old servo wires.

Type in the part # of the mosfet on digikey.com or I can send you another (I bought five).
Hope this helps.