As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MASTER WARNING BTL LOW (APU) LIGHT FLASHING INTERMITTENTLY AND CHECK FIRE DETECT LIGHT. C/W OPS TEST OF THE APU FIRE DETECTION SYS. NO DEFECTS NOTED. COULD NOT DUPLICATE DISCREPANCY WHILE MANIPULATING WIRES TO APU FIRE BOTTLE. R & R APU FIRE EXTINGUISHER BOTTLE AS A PRECAUTIONARY MEASURE IAW AMM TASKS 26-23-01-000-801 AND 26-23-01-400-801. OPS CHECK GOOD. RETURNED TO SERVICE, MEL CLEARED.