BER is a military term used for engineering equipment. including vehicles, that need repairs that cost more than the repair limit. Each piece of equipment/vehicle has an individual repair limit that reduces as equipment gets older. If estimated cost of repair is more than the repair limit the equipment/vehicle is classed as BER & is scrapped/disposed of at auction.
The main reason a repair limit is given is to stop military workshops spending far more than the equipment/vehicle is worth on repairs. BER is not really relevant on nearly new equipment as repair limit would be high, but becomes more relevant & is taken into consideration before undertaking major repairs on older ones that are coming to the end of their life. From memory, I remember vehicles having an expected life in years when they are 1st put into use.