Apple Watch Series 3 42mm Logic Board

My dad has a apple watch and he lost his email for his icloud, and we went to apple and called customer support and they couldn’t help unlock it. I have two series 3 watches, except one is pretty damaged and has a broken screen. I was thinking of swapping the broken screens motherboard with the other watches motherboard (because i like how clean the frame is on the locked one). I was wondering if anybody has tried swapping motherboards and whats the difficulty? I can take out the screen i just cant find any articles on doing this.