Depends on how current thermostat is wired. iComfort can be wired as communicating or hardwired. Post exact model of thermostat and pics of thermostat connections.
But I would first call whoever you got it from and talk to them about warranty replacement.
On the other hand, try to have Lennox send replacement to you and tell them you have your contractor install it when you get it. Otherwise, there’s a lot of places that will sell it to you.