As far as I remember there are two versions of the Big Red Button, mostly undocumented.
One works the way you want it. the other only responds to the long press.
Of course, I 'm probably wrong. The wife will confirm that
The documentation that I received is this:
Plug a lamp into an X10 Lamp Module (sold separately) and set it to Housecode A and Unit
Code 1. Plug the module into any AC outlet.
Optionally plug a Remote Siren, Model SH10A into any convenient AC outlet. Set it to A1 also.
Press the large red button on the KR15A. The lamp connected to any X10 Module set to A1 will
turn on. Hold the red button for a few seconds and the SH10A siren will start “dinging.” Hold the
button for still longer and the SH10A’s siren will sound a loud alarm. The siren will stop a few
seconds after you release the button.
It does not work like this at all.