I just stumbled across this old post from Paul Kelf...

"You can lock the Joystick & button.
It's an option in the setup (keylock).
Once selected you just hold both the joystick & button at the same time for a couple of seconds to lock & unlock"

Maybe old news for most but this'll make life easier for me
Go to Settings > Hold Key > then select Key Lock instead of Mark.
By pushing the toggle for a few seconds locks or unlocks the keys