car won't crank.

Have you checked battery and its terminals. A lot more juice is required to turn with compression.
I've seen bad starters that would start and run laying on the floor ( seemed OK ) but would not turn the engine too. That's more typical of modern mini starters. Any starter laying loose and hit with jumper cables should start with so much torque that it dang near rolled itself over. If it starts more like a fan motor, it or the amps supplied to it is the problem.