2007 Precedent suddenly wouldn't move

We have a 2007 Precedent with an Alltrax DCX 500 controller and Plum Quick motor. It was running fine until my wife parked it. An hour or so later, it wouldn't run forward or reverse. It's fully charged and Scotty's volt meter shows 51.2, the reverse buzzer sounds, though the solenoid doesn't click when the on/off switch is turned. The switch seems OK when checked with an ohm meter. I don't see any obvious loose or broken wires. That's about the extent of my electrical troubleshooting knowledge. So, I'm asking the experts to lead me through the next steps.

Thanks!!