Hard to see as the focus is a bit fuzzy, but that black piece at the end of the motor shaft should accept a tool (blade or hex wrench). Then you sit there and crank, and crank, and crank. Have never done it, but hear it is not fun!
If it could be a wiring problem you could try splicing those two wires and connecting directly to a 12V power source (preferably with a fuse in case the motor is shorted).