Sorry Gary, I can't help with the locations of the three fuses. (Boy, that's redundant circuit protection) You can use jumper cables to get power to the step motor. In fact, that's exactly what we did when we were troubleshooting the steps on our friend's coach at KOFA . We pulled someone's truck alongside the RV, connected jumper cables to its battery, then taped his multi-meter leads to the other end of the jumper cables. (Hey, you do what you have to in a pinch

)
It doesn't matter how the wires are connected, because it's a reverse polarity system, but make sure the motor is mechanically disconnected from the steps before you connect the wires to the motor's leads. if it's still connected when you apply 12 volts, you won't have the current protection when the steps reach the end of their travel, and you could pinch your fingers or gonk your coconut if the steps start moving. (Trust me on that)
If the motor spins when you connect it to power, the problem may be that the little gearbox has dryed out and jammed, like mine did. If the motor doesn't spin, you've found the problem.
Kev