Hi newbee,
Try to list the product tag identification numbers when you make a help request, because similar machines may be equipped or wired differently. Many machines have production number splits from early to late editions.
First item to go back and check is to make sure the cable connections are cleaned really well. Scrub everything clean with a small wire brush
Next, there is a large cable from the battery to the starter, follow that and look for where the smaller wire connects nearby. Carefully bridge across the two with a screwdriver and see if the starter spins the motor over normally. (That is a quick on the machine starter test, a bench test is not a loaded test)
If it does crank normally, the starter and battery connections are good. That would then mean there is likely a relay or starter switch that is having problems. Often times, simply disconnecting the starter switch and reconnecting it a couple of times will clean the connector pins, and everything start working. If that is the issue, a dab of silicone grease on the connector pins will help prevent future issues.
(I just corrected a JD 757 with this problem yesterday)
Also, follow the negative cable to where it connects to the engine or chassis and make sure it is tight and not corroded.
Hope this helps you.