As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
#1 OVERHEAT HANDLE DOES NOT ILLUMINATE DURING PRE FLIGHT TEST, HOWEVER TESTING LOOP B PRODUCES PROPER TEST INDICATIONS, LOOP A SELECTION DOES NOT ILLUMINATE OVERHEAT FIRE HANDLE. GROUNDED - YES. ACCOMPLISHED B737-800 FIM 26-10 TASK 805 NO FAULTS FOUND. CANNOT DUPLICATE WRITEUP AT THIS TIME. AS PREVIOUSLY SUGGESTED REMOVED AND REPLACED M279 ENGINE AND APU FIRE DETECT MODULE REF AMM 26-10-01. LOOP A&B TEST GOOD. GROUND VERIFICATION PASS.