What was found
PDURING TAXI OUT, PARKING BRAKE WOULD NOT RELEASE BRAKE PRESSURE. CREW CYCLED CIRCUIT BREAKERS PER MOC WITH NO HELP. MAINTENANCE WENT OUT TO THE AIRCRAFT AND MANUALLY BLED OFF BRAKE PRESSURE. AIRCRAFT TOWED TO GATE WITHOUT FURTHER EVENT. MAINTENANCE PREFORMED BITE CHECK OF THE BSCU'S AND TROUBLESHOT THE BRAKING SYSTEM PER AIRBUS TSM 32-45-00-810-806 FINDING NO FAULTS. MAINTENANCE REMOVED AND REPLACED THE PARKING BRAKE CONTROL VALVE FOR PRECAUTIONARY PURPOSES. OPERATIONAL CHECKS WERE GOOD.