What was found
DURING POWER UP/START OF APU, GOT FLASHING "AGENT DISCH" SW; NO LEVEL 3 CARGO FIRE ALERT, BUT CARGO DOOR (LOWER FWD) WAS CLOSED ALREADY AND COULD NOT BE INSPECTED UNTIL OPEN. PUSHED AGENT DISCHARGE SWITCH FOR LOWER FWD CARGO, BUT ON RETURN TO COCKPIT, HAD INDICATION BOTH BOTTLES HAD FIRED/DISCHARGED. CALLED RAMP TO NOTIFY FIRE DEPARTMENT AFTER PUSHING SWITCH. R & R BOTH FIRE BOTTLES, OPS CHECKED NORMAL IN REF TO AMM 26-22-01-5 AND -4. ACFT OK FOR SERVICE.