If you can open the case, many security devices use "odd" screws, you might find the antenna connector popped loose. Most of these connectors are press fit and not 'real' microwave cables.
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Amazon has tool kits with drivers for most security screws. I bought one for ~$10 and it's been extremely helpful in opening stuff the manufacturer didn't want outsiders to open. I've also used a drill for really odd screws when I really wanted to get inside a case.
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