As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: ON PUSH BACK AFTER INITIATING #2 ENGINE START BRAKE ACCUMULATOR WENT CLOSE TO ZERO. BRAKE PSI WENT TO ZERO AND AIRCRAFT STARTED TO ROLL. ELECTRIC PUMP REPRESSURIZED SYSTEM. BRAKE CHECK DUMPED SYSTEM PSI. NO ECAM MESSAGE DISPLAYED DURING EVENT. NO Y ACCUM LO MESSAGE WAS DISPLAYED. REMOVED AND REPLACED YELLOW BRAKE ACCUMULATOR PER AMM 32-44-11.