2007 420 won’t display reverse gear

Alright, awhile back my boyfriends 2008 Honda rancher 420 had shifting issues. His battery was bad, shift motor really nasty inside, and the shift angle sensor had high resistance when we checked it. So we replaced the battery and sensor and cleaned the shift motor and put new grease inside. It’s been great until the other day. When you shift into reverse you can hear it shift but the display only shows a — and the reverse light does not come on but it does move backwards. But tonight we were looking for beavers and he shut it off in reverse (no idea why) but when we went to leave it wouldn’t shift into neutral and it wouldn’t start either when he held the brake and tried starting it. Any ideas what could be wrong, especially with the reverse indicator? Any help is appreciated, I searched everywhere but didn’t find anything