How to power-off Motorola phone without screen How would one power down an Android phone (Moto X 2nd gen - Android 5.1) without the ability to interact with the screen? USB debugging not enabled, nor is custom recovery.

I know how to reboot it, that is not the question.  The question is about turning off, not restarting, the device.

The phone has a broken screen (black screen, blank screen, cracked screen) and also does not respond to touch, so the answer should not include any screen interaction.

Is there a series of button presses, timings, and preconditions (if applicable) if executed will leave the phone in a true power off state?
I can't be sure that this is the optimal way to power-off the phone, but it seems to work.


Press and hold power until it buzzes or about 15 seconds, then
release. 
Press and hold volume-down and the power button for 20
seconds, then release.  
Press and release the power button once.


This procedure is demonstrated in a you tube video https://youtu.be/x_jx5u7dXK4

Tip: Even though the broken phone has no display functionality, if you view the phone with another camera, you can check activity of this phone by looking at the infrared emitters at the four corners of the device.  Before power-down, these dots will be flickering.  Afterwards, no flickering.