Car Will Not Start problems of the 2012 Audi Q5

Tl- the contact owns a 2012 Audi Q5. The contact stated while stopped at a traffic light, "the "change key battery" warning light and the engine stalled suddenly. The vehicle would not restart while the key was in the ignition,however, it restarted when the key fob was pressed on. The problem occurred once. The vehicle was not taken to a mechanic for a diagnosis,however,she contacted the dealer and explained what had occurred. The service manager had informed the contact that when the battery was not charged in the key fob,this could happen and has been happening for years. The key fob was repaired. The manufacturer was not notified of the failure and the approximate failure mileage was 12,000. Gb.