As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 2354. AFTER SAFETY AND POWER UP CHECKLIST, CRG AFT FIRE SYS FAIL CAUTION. REMOVED FROM SERVICE. PERFORMED FIM 26-15-00-810-804-A. FOUND TO BE TRANISTORY AND IN CORRELATION OF CB POP REF LP DEFECT 1084752 FOR CUSTOM IO 2A MAU 3. NO FURTHER DEFECT. RETURNED TO SERVICE