As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER STOPPING AT GATE AND DEPLANING, SMOKE STARTED COMING OUT OF OVERHEAD PANEL ABOVE 21A. PULLED ALL CABIN LIGHTING C/BS. FOUND CEILING LIGHT BALLAST BETWEEN 21 AND 22 ABC BURNT UP. DISCONNECTED SAME FWD TOMCO AND PLACED PER MEL 33-00-02. BALLAST WAS SUBSEQUENTLY REPLACED, OPERATION NORMAL.