Press and hold the Volume Up and Power buttons at the same time until the screen turns off, then release both buttons —this should take about 15 seconds. The screen may flash the Surface logo, but continue holding the buttons down for at least 15 second
To completely shut down Surface Pro 3 or Pro 4 and restart it, press and hold the Volume-up button and the Power button at the same time for 15 seconds and ...
Shut down your Microsoft Surface totally. Press and hold both the Volume Up button and the Power button at the same time for about 15 seconds. Release both ...