Walkie-Talkies w/ Arduino for remote cut-off

So I have a pair of walkie-talkies, and I was going to wire one of them to work as just a receiver and one to work as just a transmitter, so I could make a remote kill switch for my go-kart. However, when using the call button on this model, it disables itself after a few seconds. I have Midland Xtra Talk LXT500 walkie-talkies. Is there a way to bypass this auto-shutoff, or to hot wire across the microphone input so it will always think it's receiving some high-volume signal, then I can just install a latching switch for the PTT button instead of momentary one? If there's a way to bypass the shutoff, what would I look for on the PCB? Some sort of capacitor, I imagine? I've attached a couple pictures, hope something shows up. Also, more inductors are present than I would have imagined normally.