1) check all fuses
2) check that the mid-pto is in the off position
3) check all fuses
4) check that the rear PTO is in the off position
5) check all fuses (shorted is "good" - open is "bad")
6) check that the HST peddle is in the center
7) check all fuses
8) check that the cruise control is off
9) check all fuses
10) check that the clutch is going down all the way
if that does not work, you can try checking the fuses. Might be a bad one.
But seriously, the symptoms are either a safety switch is engaging or a blown fuse.
Dead / weak battery will chatter the solenoid and dim the head lights when attempting to crank. Safety switch or fuse will give no indication that the key was turned.
Cranking with no start is potentially the kill switch pulled out.
While frustrating, it's probably a simple fix and that's good!
jb