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

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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.
(1) Answer
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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