Its quite interesting that I have not seen an answer to the Differential Brakes problem other than: not following procedures; not installed properly or something that indicates user error. Well, I am here to tell you this is not user error. Here is my story, lol:
Did a late evening flight from KPHL to TXKF in the Airbus 320. Left Philly with no problem, landed in Bermuda, no problem. Taxi. Park. Disembark (hey that rhymes!). Parking Breaks on, Chocks, Cones, APU on. I leave the plane as I go into the terminal to find something to eat (went in my kitchen to cook dinner).