How can I turn off iPhone 6 completely without using the poser button nor screen?

[iMore Question]

The screen function of my iPhone 6 is disabled. I does turn off when I push the power button, but I want to reset/turn completely to see if the function could restore. However, I do not know how to power off/reset completely.

 

[kataran]

Holding down the power button gives you a power off slider on your screen but if it's unresponsive you can not turn it off

A hard reset

Hold down the power button and the home button at the same time till the screen goes dark will power cycle your device