What was found
CREW REPORTS APU FIREX FAIL EICAS MSG (APU FIRE EXTINGUISHING SYSTEM). REMOVED FROM SERVICE. T/S APU FIREX FAIL EICAS MESSAGE (FAULT CODE: 26220047UT1). PER E175 FIM 26-22-00-870-803-A, PERFORMED ELETRICAL TEST OF APU FIRE EXTINGUISHING BOTTLE PRESSURE SWITCH (TCPS) IAW E175 AMM 26-22-03-720-802-A. ELETRICAL TEST FAILED. PINS A AND C ON THE APU FIRE-EXTINGUISHING BOTTLE TCPS SHORTED (FAULTED). AND PINS A AND C HAVE CONTINUITY TO GROUND (FAULTED). REMOVED APU FIRE BOTTLE REF E175 AMM 26-22-01-000-801-A. INSTALLED NEW APU FIRE EXTINGUISHING BOTTLE IAW E175 AMM 26-22-01-400-801-A. PERFORMED OPS TEST ON APU FIRE PROTECTION SYSTEM REF AMM TASK 26-0-00-700-801-A. OPS CHECK GOOD. RETURNED TO SERVICE.