As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA- ON FLIGHT NUMBER 2478, FIRE SYSTEM FAULT STATUS MESSAGE APPEARED FOR 20 MINUTES AND THEN EXTINGUISHED. FOUND MDC MESSAGE AFT SMOKE DETECTOR 1 FAILED WIRING NO RESPONSE TO COMMAND IN FAULT HX. REMOVED AND REPLACED SMOKE DETECTOR. OPERATIONAL CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.