As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 5338 - IAD - FLIGHT CREW REPORTED MAIN BATTERY NR 1 OVERTEMP IN FLIGHT, REACHED 74C AND HIGHER ON GROUND BEFORE SHUTDOWN. CREW DECLARED EMERGENCY. IAD MX REMOVED AND REPLACED NR 1 MAIN BATTERY AND PERFORMED OPERATIONAL CHECK SUCCESSFULLY. ACFT WAS APPROVED TO RETURN TO SERVICE.