Something as simple as a stuck throttle pin will hang up the grip and wont allow the VM to see neutral. HPD is high pot disable. Most brands have this in case the throttle is twisted on and you close the deadman switch, the truck may launch fwd. You get code "HPD"
Check the twist grip operation, it should snap back to the middle easily in either direction. If not, take it apart and check for a roll pin backing out on the grip wire, hitting the throttle bearing. Very commom. Code C30 is belly button switch. It's most likely broken. Do not try to fix as the plastic piece cannot be straightened and will cause grief!. Removing it completely will stop the code though. As long as it's in the wrong spot, truck wont move. C35 is brake switch out of adj. It may be on with handle up or too far down out of adj. Make sure spring on handle can lift the handle up all the way...they often break! I think you have a collision damaged truck that can be fixed easily.