As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB-OUT, HEARD A "POP" SOUND LIKE AN ELECTRICAL RELAY OPENING. ALL PASSENGER OXYGEN MASKS IN CABIN DEPLOYED FOLLOWED BY O2 SWITCH LIGHT. AIRCRAFT RETURNED TO DFW. REMOVED AND REPLACED CABIN PRESSURE CONTROL PANEL IAW CRJ AMM 21-33-01. OPERATIONAL CHECK GOOD, PERFORMED FUNCTIONAL CHECK FLIGHT WITH NO DEFECTS. RETURNED AIRCRAFT TO SERVICE.