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

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?