questions;
1, did the extern siren go off on its own ?
2, is the power LED on (the green one) ?
3, did the system respond at all to your code ?
4, how old is the system
5, jhave you changed the back up battery in the panel latley, ?
6, Is there a TAMPER or PA LED lit
yes the external sire unit has a back up battery, depending on the make/model it could be one of about 4 or 5 different battery sizes
panel battery should be (old money 2.8 AH) 3.2 or 3.1 AH 12VDC
if the battery in the external siren unit has failed it will `lockout` the keyp[ad, this can also happen if the battery in the control panel has failed.
hope this helps
John