As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EWR - CREW REPORTED CABIN FILLED WITH GREY ELECTRICAL SMOKE. EMERGENCY DECLARED LANDED EWR WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND BURNT BALLAST AT ROW 8-9 AND DAMAGED POWER PORT CABLE AT SEAT 7-8. REPLACED BALLEST CONTROLLING SEATS 8-AB AND 9-AB OVERHEAD CEILING LIGHTS. REPLACED SEAT TO SEAT CABLE BETWEEN 7-DEF AND 8-DEF. SYSTEM GROUND CHECK NORMAL OPERATION.