As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 678 LAX-JFK, CREW DECLARED EMERGENCY DUE TO AUTO BRAKE AND NORMAL BRAKE SYSTEM INOP AFTER GEAR EXTENSION. ALTERNATE BRAKES WORKED OK WITH NO OTHER INDICATIONS ON ECAM. FOUND DELTA P ON GREEN HP FILTER POPPED. REMOVED AND REPLACED GREEN HP FILTER, CASE DRAIN FILTER AND NR 1 HYD PUMP GREEN SYS IAW 29-11-51-04. OPS AND LEAK CHECK GOOD IAW 29-11-00.