Mtroniks have rightly an excellent reputation for customer support and are always worth a phone call. They will help you in any way they can and give to the best advice. As Ashley says the newer type do not need a button to be pressed to set up, whereas the older versions were fitted with a small button that was pressed during set up.
With the older versions you pressed the button during the first couple of seconds after powering up and then followed the process of moving the stick up, press the button, down, press the button and then centralise. If it doesn’t respond then maybe a new one is the best option. I take it your transmitter lever does return to the central position by spring and it has never been used to control a sail?