As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 3900 THE CREW REPORTED THE FLIGHT ATTENDANT CALL BUTTON LIGHTS FOR ROWS 7, 8, 9, 10 CAME ON UNCOMMANDED FOLLOWED BY REPORTS OF FUMES AND POSSIBLE LIGHT SMOKE. THE LIGHTS REMAINED ON UNTIL AIRCRAFT POWERED DOWN. THE AIRCRAFT LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS REMOVED FROM SERVICE. FOUND BURNT PRINTED CIRCUIT BOARD CARD AT SEAT 7BC. REMOVED AND REPLACED THE PRINTED CIRCUIT BOARD CARD IAW EMB MM 33-25-04. THE OPERATIONAL CHECK WAS GOOD. THE AIRCRAFT WAS RETURNED TO SERVICE.