As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PASSENGER OXYGEN MASK PANEL OPENED IN FLIGHT ABOVE SEATS 2C AND D. FWD TO MEL 35- 21-01A. M PROCEDURE C/W AND PLACARD INSTALLED. SEATS 2 C AND D UNUSABLE. RESECURED O2 CONTAINER DOOR AT 2CD PER AMM 35-21. M PROCEDURES REVERSED. MEL PLACARD REMOVED. OK FOR SERVICE. (LP: 8838650, AIRCRAFT WAS GROUNDED)