If your iPhone 7 stops responding, you can’t turn it off by holding down the power button. The iPhone 7 doesn’t have a physical Home button, so the method for forcing a restart, or a hard reset, has changed.
- Press and hold down the On/Off button on the right side
- While continuing to hold the On/Off button, press and hold the volume down button on the left side of your iPhone.
- Hold both buttons as the screen turns off, and keep holding them until the screen turns back on and displays the Apple logo.
Note: 9/12/2017 will be introduced new iPhone version. So we will be ready to find out and publish how to reboot iPhone8 (or maybe how to reboot iPhone X)