As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER REPLACING CABIN FIRE EXTINGUISHER (WATER) FOR HYDROSTATIC DUE DATE, WE ATTEMPTED TO TO USE THE WATER FIRE EXTINGUISHER THAT WAS COMING DUE FOR HYDROSTATIC TESTING AS A TRAINING AID. FOLLOWING THE INSTRUCTIONS PRINTED ON THE BOTTLE, AN ATTEMPT TO DISCHARGE THE EXTINGUISHER WAS MADE AND THE EXTINGUISHER DID NOT FUNCTION.