It sounds like you may have a problem with the battery, and as it's over a year old, I doubt that it's a LiFePO
4 pack.
If the battery gauge lights on the throttle go out completely, the battery
(or a poor connection) is the most likely cause.
If the lights come on again by simply switching the battery off and on again, it will probably be the
BMS that has disconnected the battery because of a low cell or battery voltage.
Alan