I have a very old alarm system and I broke the 12v internal sounder while decorating. Everything still works but I only hear the faint beeping from the remote keypad when setting and entering. Outside sounder still fine. I bought a new piezo sounder, connected it up and ...nothing. Tried it directly onto the. 12v battery inside the alarm and just got an initial squeak/scratchy sound but no siren. Tried it on the battery of my car and it’s fine. Why won’t it work on the internal sounder to alarm battery? Could it be faulty?