Assuming your momentary switch (button on the wall) still works, you can make it wifi compatible for about $15. All you need is a 120V relay and a wifi socket. Basically, wire up your relay so that when activated, it completes the circuit (in parallel with the existing button) on the garage door opener. The way you trip the relay is by sending a "turn on" command to the wifi socket which is powering the relay. Because the garage door needs a momentary switch, you'd set a command in the wifi socket's app to immediately "turn off" the wifi socket 2 seconds after receiving the "turn on" command.