As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED SMOKE APPEARED MOMENTARILY IN CABIN AT PUSH TIME. MAINTENANCE FOUND THE NO SMOKING FASTEN SEAT BELT SYSTEM INOPERATIVE WITH THE ROW 6 ABC OVERHEAD PSU BASE ASSEMBLY SHORTED OUT. THE WIRES FOR PSU AT ROW 6 ABC WERE CUT AND STOWED AND THE SYSTEM WAS PLACARDED INOPERATIVE.