As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(B-18208) DURING PUSHBACK, APU FIRE MSG DISPLAY AND ALARM INTERMITTENTLY THEN APU BOTTLE LOW PRESS MSG DISPLAY. GROUND BITE TEST FOUND BOTTLE DISCHARGED, BUT NO LOOP MESSAGE. APU COMPARTMENT INSPECTED NO FINDING. A/C RELEASE WITH APU ENACTIVE.