Is it possible that you could have bumped the PTO switch while turning on the lights? Just a thought, sounds like something I would do and not think to look at!

I checked the PTO switch and it is in the off position. This has me baffled.

Check battery connections first.

10amp is headlights.
20amp is tractor harness.

Prob have a safety switch issue, could be the neutral sw or pto or key sw or even one of the relays. Been a good long while since I worked on one of these.

Is the tractor in neutral? Cycle the shifter,then back to neutral.