As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW PERFORMED AN AIR TURN BACK. ALL LT SIDE PASSENGER O2 MASKS DROPPED. CABIN PRESSURIZATION NORMAL. MAINTENANCE REPLACED R2-315 RELAY. RESTOWED MASKS AND PERFORMED DROP TEST IAW AMM. ALL O2 MASKS DROPPED NOMALLY. ALL OPERATIONS NORMAL.