As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MZJ - ON FIRST FLIGHT AFTER C4 CHECK, DURING CLIMB-OUT, AT 29,000 FEET WITH 8.0 PSI DIFFERANCIAL PRESSURE, SIDE CARGO DOOR LIGHT ILLUMINATED ONCE. DEPRESSURIZED, AND LIGHT WENT OUT. (AIR TURN BACK) ADJUSTED LOWER DOOR CLOSED SWITCHES PER B747 MM 52-71-00 PAGE 505. REMOVED AND REINSTALLED GILL LINER FOR ACCESS PER B747 SRM 51-30-02. (M)