If it were me, I would want to know the voltage of the batteries after the charger shut off. Also the voltage of each battery after that 5 mile ride.
I would
invest at some point in a nice multi meter.
That said...
There is a procedure to reset the OBC.. It seldom, but sometimes gets results.
Reset the club car OBC
OBCs always struck me as a ridulous amount of money. Almost worth getting a new 'smart' charger and bypassing the thing.
Replacement On-Board Computers for Club Car Golf Carts | BuggiesUnlimited.com