Out Of Charge
The vehicle has run out of charge.
Nothing a policy can do at the vehicle will change that: charge is a function of the odometers, so the only way back into service is to reach a charger, which means towing. A policy that does nothing leaves the vehicle flat and the framework takes it out of service -- which is the right answer and the honest one, because a vehicle that has run flat on a guide path is an obstruction for the rest of the run.