Well, you've confirmed that the problem is with the electrical system somewhere.

I wouldn't open the mechbox first, as the problem may not be in there at all. I'd check the externally accessible stuff first. Check the fuse. If it isn't that, I would proceed to test the motor on its own to see if it works connected directly to a battery. Then you could either rule out or confirm that you may have a dead motor. If that's the case, then you've solved the problem without having to open the mechbox.

If you have some speaker wire, cut 2 strands a couple of inches long and strip the ends. Insert the wires into the connector on the battery to make positive contact with the contacts inside. Then, making sure of polarity, briefly touch the other ends of the wires to the power terminals on your motor. If the motor fires, it's good. If not, then the motor is dead and you've found your problem.

If the motor is good, then you should look at all the external wiring in detail, then open the mechbox and check the terminals as Cdn_Stalker said.

also... when you put back your motor... make sure you put the right wire on the right terminal.. + + , - - .... I learned that in the hard way..