As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED DURING CRUSE FLT SMOKE ENTERED COCKPIT FROM AC ELECTRICAL PANEL AREA. NO SYSTEM MALFUNCTION WAS NOTED. NO ELECTRICAL POWER WAS LOST. ONCE ON GROUND DC POWER COULD NOT BE TURNED OFF THROUGH NORMAL SWITCHING. BATTERY WAS DISCONNECTED TO REMOVE DC POWER FROM AIRCRAFT. MAINTENANCE HAS DISCOVERED THAT SMOKE CAME FROM CONNECTOR J31, LOCATED IN LEFT OVERHEAD PANEL IN COCKPIT. CAUSE IS STILL UNDER INVESTIGATION.