Alrms goes off in the garage then battery dies on 1999 Jaguar Vanden Plas

We have an issue lately with our cat. The alarm goes off by itself (no one and nothing near) and the battery dies. Any thougts as to where I should start looking.

Asked by for the 1999 Jaguar Vanden Plas
If you have an aftermarket alarm system, I recommend removing it. I've had to eliminate many of those in my career.
If it's original Jaguar equipment, find a Jag specialist or an auto elelctric shop for help.
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