As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE WAS NOTED FROM OVERHEAD PSU PANEL AT ROW 4 WHILE EN ROUTE FROM CGN TO EWR. HALON AND WATER FIRE EXTINGUISHERS WERE USED ON THE OVERHEAD AND THE AIRCRAFT WAS DIVERTED TO SNN WHERE IT LANDED WITHOUT INCIDENT. TROUBLESHOOTING FOUND PSU AT ROW 4 WITH A BURNT CIRCUIT BOARD. MEL WAS APPLIED TO PSU 3EF AND 4EF.