As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
YQX - INFLIGHT LHR-BOS. CARGO DETECTED AIR STATUS MESSAGE APPEARED DURING FLIGHT. EMERGENCY DECLARED, LANDED YQX WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED NUMBER 1 AND 2 FORWARD CARGO DETECTION FANS. SYSTEM GROUND CHECK NORMAL OPERATION.