I am building my own 3d printer based on tevo tornado / cr10s . I have everything up and running minus the 3d touch . I have followed all the vidoes and tutorials i can find and still not working. When I power up the board is does it self test and when its done it stays with red light on and probe retracted . I do a M119 command the z axis shows open . I unplug the probe from my board I do a M119 command and it shows z axis triggered . What could I be over looking .