Chosen Solution

How do i power off my iPhone so I can fix the screen. Home button non-functional, screen non-functional.

Frankly I would just let the phone drain its battery until it shuts off. Is your power button broken too?

If Screen is going to be changed and your wanting to power off phone so you don’t blow a backlight which is the right thing to do. All you need to do is open the screen and disconnect home key the unscrew the battery bracket and disconnect the battery. Once you have replaced your screen you can then connect battey and screw the bracket back it and then connect home key. start your phone and your good to go. Cheers.