As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLL - AFTER CLIMBOUT FROM FLL, AT FL250, CAPTAIN REPORTED THE CABIN ALTITUDE WARNING SOUNDED. THE LEFT PACK WAS ALREADY ON MEL, SO CREW ADVISED ATC ACFT HAD AN EMERGENCY AND WANTED TO RETURN TO FLL. CABIN WAS ADVISED AND THE FLIGHT RETURNED TO FIELD AT FLL. FLIGHT LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REMOVED AND REPLACED THE RIGHT PACK FLOW CONTROL VALVE PER MM 21-51. LEAK CHECK AND OPERATIONAL CHECK OK.