Before you get under the car again turn the engine at the big front crank bolt. Move it enough to rotate the bolt ~15 degrees. Try the starter. If it does not turn the engine move it another 15 or so degrees and try again.

If you rotate the flywheel the entire 360 degrees and the engine won't turn at all it suggest a bad starter drive. If you find a place or two with which the engine turns then the starter is doing it's part and the flywheel will have to be replaced.

I ordered a USB endoscope from from a place called Banggood online. It may have been the best 10 bucks I ever spent.

__________________
84 300SD
85 380SE
83 528e
95 318ic