basically wht it boils down to is one of 3 things then, your 4 in 1 is blown, and you need a new 7313 mosfet if you can repair it, or you're out 50 bucks for a new one, the next thing it could be is both of the motors are shot. If this is the case likely the 4 in1 is also shot, lastly and least likely is that your motors are somehow unplugged.