As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OVERHEAT LIGHT IN PACK NR 3 FOLLOWED BY AREA -C- OVERHEAT WITH PACKS 1 AND 2 RUNNING SMOKE STARTED ENTERING CABIN. TURNED NR 2 PACK OFF AND OPENED DOORS SMOKE SEEMED TO DISSIPATE SOME. UNABLE TO DETERMINE SOURCE OF SMOKE. LOCKED OUT NR 3 PACK ISOLATION VALVE PER MEL 21/21/01A.