2008 GT door and trunk buttons do not work nor does keyless ignition

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Mazda MX-5 2008 GT
My 2008 GT drivers exterior door entry button quit working. A few months later, the passenger button, trunk button and the keyless ignition quit. My credit card remotes work but I still have to use the physical key to start the car. My dealer wants $145 just to diagnose the problem. Any suggestions?

Thanks
 
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