As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO DFW DUE TO THE FLIGHT CREW REPORTING WITH THE RIGHT PACK ON MEL THAT DURING CLIMBOUT THE LEFT PACK OVERHEATED RESULTING IN THE LOSS OF THE REMAING PACK LEADING TO A LACK OF PRESSURIZATION - THE AIRCRAFT LANDED SAFELY AT DFW WITHOUT FURTHER INCIDENT - MAINTENANCE REPLACED THE TURBINE BYPASS VALVE 10HH ON THE LEFT PACK PER AMM 21-63-53