Here are a couple of other easy things to try:

Jiggle your J-gate, that is run the lever through the full gate, (but try not to have too much fun). Sometimes the cable that operates the transmission can get out of adjustment.

Look under the car and see if the ground strap that bolts to the transmission is firmly attached.

These are two problems that I discovered on my non-starter. Good luck.

 

did you find the cause?