I don't have the HPX, but here is a link to an online manual (guessing newer model but probably will work for yours): https://manuals.deere.com/cceomview/O...dex.html?tM=HO. Check out the "Checking and Replacing Fuses" section. Hopefully the picture matches what you see.
I don't know that grounding the wire would achieve your desired goal - try shorting between leads of the switch instead (assuming you haven't blown a fuse by grounding).
Best of luck and maybe somebody with an HPX can chime in. (Or maybe I can learn more by looking at my XUV when I get a chance, but it won't be before the weekend.)
- Steve in CO