trigger android hardware back button in code

I have my own back button and maintain a navigation stack. If I pass back through that stack and the user taps my back button again, I want to trigger the hardware back button press - Finish the activity. From within my ContentPage I tried to call OnBackButtonPressed(), but it just returns false. Should this work? Is there a better way to trigger a button press?

    private async void BackTappedCallback(object o)
    {
        if (App.Navigation.NavigationStack.Count > 1)
            await App.Navigation.PopAsync();
        var onBackButtonPressed = OnBackButtonPressed();
    }

Thanks!