Apple Series 4 watch repair

My series 4 apple watch has a cracked screen. I want to replace it, but i can not turn the watch off. The two methods listed on how to turn it off do not work. If i replace the broken watch face, and disconnect the watch face to put on a new one while the watch is on, will the watch work when the new screen is on, will if power back up, or once i disconnect watch with power it is dead for good?