[Tommy]

It sounds like you have a plan. If you do bypass the normal systems, be sure to do it safely so the car doesn't move, and nothing gets caught up in moving parts when the starter turns.

A typical starter is connected to a large cable from the positive terminal of the battery and a ground through a large cable from the negative terminal of the battery to the starter case or the engine nearby. One way to test each of these is to run a jumper cable between each end of a cable. You don't even have to disconnect the existing cables, but its best to do this one cable at a time. If the starter works with the jumper on but not off, you've found the faulty cable.

The other test is to run a jumper from the positive battery terminal and briefly touch it to the solenoid connection that should be energized when the starter switch is engaged. (Don't forget the safety concerns above.) If the starter turns over normally using this method, the problem is somewhere in the starter wiring circuit (i.e., ignition switch, starter switch, wires).

If you try all three of these tests and the starter won't turn normally, I'd suspect the starter/solenoid itself.