As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MASTER WARNING LIGHT ILLUMINATED WITH CARGO FIRE LIGHT. ALL THREE CARGO FIRE LIGHTS ILLUMINATED ON THE SDS PANEL. EMERGENCY DECLARED FLIGHT RETURNED TUL LANDED WITHOUT INCIDENT. REPLACED CARGO FIRE MAINTENANCE UNIT. SYSTEM GROUND CHECKED NORMAL.