Reset iPhone/iPad

1. Turn off device. Press and hold both the side button and the Volume down button until the power off slider appears.
   
2. Put device in recovery mode.

   Connect the cable to your Mac or Windows PC. Next, connect the cable to your iPhone and quickly hold the side button. Do not release it.

   Continue to hold the side button while the Apple logo appears. Do not release the side button until an image of a computer and a cable appears.

3. Reset. Using "Apple Devices" app select Restore, then Restore and Update.