As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOS - DURING CLIMBOUT CREW REPORTED SMOKE IN CABIN AND COCKPIT SMOKE ALARM ILLUMINATED. EMERGENCY DECLARED RETURNED BOS WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED LEFT AND RIGHT RECIRCULATION FANS AND HEPA FILTERS. REMOVED AND REPLACED LEFT PACK FLOW CONTROL VALVES. SYSTEM GROUND CHECKED NORMAL OPERATION.