A319 First Officer reported brake problems on taxi out resulted in a return to the gate which required the aircraft being towed back to the gate instead of taxiing under power.

Narrative

I was flying with Captain Name and we were taxiing for takeoff on Aircraft X ZZZ to ZZZ1 on Date at approximately XA:00pm CDT. When arrived at the Aircraft Maintenance Personnel were working on the Aircraft due to a write up from the previous crew regarding brake system. During the taxi out the brakes were locking up on both brake pedals and the plane was violently dipping it's nose. We decide to stop the aircraft and set the parking brake and shut off the engine on Taxiway 1 just short of 2 in ZZZ. We turned on the APU and waited to be towed back to the Gate. Captain wrote the plane up and we left after debriefing the maintenance technicians. When I was doing the preflight the Maintenance Personnel asked me if I saw anything wrong with the brake system. Also; they returned to the flight deck three times during the boarding process to check on the plane. Usually; this doesn't happen. They fix it and leave. The BCSO (Brake Control Shut Off) faulted out which caused our number two brake to lock up and slid down the taxiway. I'm glad it happened on the ground and not on landing. We never received an ECAM or any alert to our failure; which is not typical in the Airbus. More research on known brake issues. I don't think the mechanics were happy with their fix to the situation. Hence them returning and waiting for the plane to leave before their departure.