Geezer I talking about option51 , 17 restart
I think you eaten to many samosas the galaxy which has its quirks has this feature and solves the odd bug
Stop trying to be an alarm monkey
If both are marked T, then either take the white back to 0v in the panel too, or just remove the white wire and place a wire link from that 'T' connection in the siren to the black 0v in the siren.