RADROVER 5 No power "P" showing in display

[Grizzly Granny]

My husband has a RADROVER 5, not quite a year old. On ride today, motor power stopped suddenly.  A "P" is showing in his display where the wattage should be.  All connectors tight, battery full.  He had to ride all the way back to trail head under his own power.  We have diligently searched the internet and owners manual and also YT.  Nothing. We called RAD Power Bikes customer service 4 1/2 hours ago, got into the queue to receive a call back and not lose our place in line, and still no call back. That seems excessive. Does anyone have any experience with or thoughts about troubleshooting this issue?  G.G.