Remember, you should have a 4 or 5 wire switch. That switch REVERSES the 12 volt polarity to make the motor turn one way(extend) and Reverses when you retract. So, you can have a short on 2 wires and not just 1. When the switch reverses the Neg wire is now positive and when reverses the other way the OTHER negative wire now becomes positive. So it appears you have drilled holes into the 2 wires coming from the switch to the motor. You may just have to go inside and cut an access hole in the interior wall behind where you drilled and installed the new screws. Just make the access hole smaller than a 4 by 4 blank wall plate. Doug