As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 711 KMIA/MMMX, DURING CLIMB AUTO PRESSURIZATION FAILED, WENT TO STANDBY, OUTFLOW VALVE WENT FULL OPEN. UNABLE TO HOLD CABIN PRESSURE IN MANUAL AC OR DC. AIRCRAFT RETURNED TO KMIA AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND CABIN PRESSURE CONTROLLER SENSE PORTS CAPPED. REMOVED CAPS AND PERFORMED OPS CHECK PER "B" CHECK WORK CARD 7-29 AND B-727 MM 21-30-0. AIRCRAFT RETUNED TO SERVICE.