As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE HOLDING FOR T/O DURING CROSSBLEED START OF NR 3 ENG. AFT CARGO SMOKE WARNING AND BELL ACTIVATED. FIRED NR 1 FIRE BOTTLE INTO AFT CARGO COMPARTMENT. WARNING STAY ON. INPS AFT CARGO COMP. NO FIRE OR SMOKE. *S/D* REMOVED AND REPLACED AFT CARGO COMP CONTROL ELECTRONICS UNIT PER MM 26-16-012. SYS CK OK. REPLACED AFT NR 1 FIRE BOTTLE PER MM 26-16-014-2.