Continuing from part 1... here's the power cable attached to the bottom of the board.
Check the voltage on the power pads, you should see full battery voltage. You'll also notice that the positive pad is on the right looking down with the arm pointed at you.
This worked well and is what I recommend you do. (update: brosius85 points out that the motor windings are coated with varnish that's heat-resistant in order to handle the high temperatures of the motor. That's why I couldn't just burn off the coating with the soldering iron. Thanks Brosius85!)
Continued in part 3...