As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN BAQ WHEN EXTERNAL POWER WAS CONNECTED SMOKE CAME INTO COCKPIT FROM OVERHEAD PANEL. AS PER AMM 20-50-01 PAGE 201, GROUND ELECTRICAL 106 LINE WAS ISOLATED ON CONNECTOR P1-568 OF CABIN PRESS SELECTOR ELECTRICAL LINES WERE CHECKED BY CONDITIONS ON OVERHEAD PANEL WITH SATISFACTORY RESULTS.