Shot the sounder?.
There's several omnicrom models one of which is a wireless jobbie.
The early omnicroms simply used key presses for a factory default,
Eg enter engineers code then hit the zero key.
The factory engineering default code is 9999 if that helps,but chances are it's been changed and probably not running on programming defaults.
Can't give you a link for the engineering books, so try the net because you will need one for instructing you how to default user/engineering codes and also for programming.
e manno, November 2013