Dell XPS 12 :: Refused To Turn On After Going Into Sleep Mode

My Dell XPS 12 has twice refused to turn on after going into Sleep mode.  There is no indication of activity at all.  This happens when I know that the battery is nearly fully charged, and continues even after plugging in the adapter.  The adapter works just fine to charge the battery and the battery typically runs for at least 6 hours so I do not believe that or the battery are the problem.

The first time this happened, I continued to open/close the lid and try turning on the computer.  After several hours, the computer turned on and worked just fine.  I had already scheduled service with Dell before I got it to turn on and Dell's technician replaced the motherboard under the assumption that that was the problem.

The second time I again continued to open/close the lid and try the power switch after contacting Dell and scheduling service.  The next day, after several tries, the computer started up and again is working normally.  I am not allowing the computer to Sleep and am using Shut Down instead.  Dell has ordered a replacement motherboard (yes, again), battery, and DC IN.  I don't think that this is a power issue so doubt that any of those will fix the problem. 

Does the XPS 12 have a "lid sensor"?  Something that could fail to recognize that the lid is open and could be turned on?