As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING L/O SERVICE, OPERATIONAL CHECK OF FWD CARGO COMPARTMENT NOTICED SPARKS AT STATION 500 UNDER FLOOR MATT AND THE FOLLOWING C/BS POPPED AT P35 PNL C166, C168 AND C169. MAINTENANCE IN PROGRESS REPAIRING WIRING. DAMAGE TO WIRING CAUSED BY A SPARE CARGO LOCK FALLEN INTO THE BOTTOM OF THE CARGO COMPARTMENT AND CHAFING ON WIRING.