Ave you tried starting it with a jumper button on the starter motor, bypassing the key? If so does it turn over then?
Have you check the fuseable link? I had a vw that blew the link, power went threw in with a meter/test light but not enough to amps/voltage were allowed to go thru. Same kinda deal/issue that you have right now. It was in the power line to the starter, just a thicker portion up near the battery. I cut out the link and terminated it to the battery, no more issues.