Dalton, turn the motor shaft with your fingers -make sure machine is unplugged-. You can slightly assist the motion by -gently- turning the turntable flywheel in the same direction but the main force must come from turning the motor.
I agree with Ron re: the relay. This was where we were going before. What may have happened is that during your friend cleaning the contacts he may have pushed them too close together but not gotten all the pitting out. Once power was applied and the motor reversed the contacts sputtered and welded. I have seen this happen on regular reversing switches (the tail on the mech) when someone though they could just bend the blades together instead of properly servicing them.
What happens on the reversing switches is that if one set of contacts don't 'break" before the others make it throws a dead short across the line.
The service outlet is for soldering iron, work light etc.
Rob