As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
YQX - INFLIGHT BOS-CDG. CREW REPORTED BATTERY CHARGER STATUS MESSAGE ILLUMINATED DURING FLIGHT. EMERGENCY DECLARED DIVERTED YQX LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED MAIN BATTERY AND MAIN CHARGER. SYSTEM GROUND CHECKED NORMAL OPERATION.