Dell Chromebook - power button does not work

We have confirmed that some power buttons have stopped working on student Dell 3100 2-in-1 Chromebooks. The Chromebook still works properly and will turn on and off by opening or closing the LCD screen.  If the Chromebook needs to be reset (after using the NWEA app, for example), press and hold the following keys:
Alt + R + volume up*

Release the keys after the screen turns black.  The Chromebook will begin to restart after a few seconds.

*This will not work by pressing the volume button on the side of the Chromebook.