As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
#1 FIRE HANDLE NOT LIGHTING UP WITH FIRE TEST. GROUNDED - YES. #1 ENGINE LEFT CORE DETECTOR UPPER HARNESS BROKEN OFF AT LUG. REPLACED HARNESS MW0326 REF B737-900 AMM 26-11-02-400-802 PARA 5. I. OPERATIONAL TEST PASSES REF AMM 26-11-00-710-801. GROUND VERIFICATION SUCCESSFUL.