But when it’s the on/off button on the side of an iPhone or iPad, users are in trouble. Luckily, there’s still a way to turn the device on and off until it’s repaired.
Under iOS 11 the path is Settings > General and then scroll to the end of the list where you’ll find the option Shut Down. If you select it, the normal shutdown screen is presented and the device can be turned off with a finger swipe.
To switch the device on without using the button, just connect the device to a charger using a Lightning cable. — dpa