Most of the batteries were removed for low charge state. ie the towing switch left on or extended tows using the lights and brakes.
A full charge of the batteries will give approx 1hr use of power to the ACP, exterior lights, flt deck dome light, and brakes. This drops significantly with a lower voltage state. (15mins at 29.7v)
IIRC One of the 'failed' batteries, the a/c had dispatched with a battery message (that was at the time a MEL item).