I followed the steps as presented by Dell-Chris M and described by peterwbaker as above and I fixed the issue. In my experience of having system restarting many times, the critical notes in fixing this are: (1) to disable the Auto BIOS Update when install BIOS 1.6.0, and (2) using the right-click mouse command "Run as Administrator". Hope this helps.
Hello, I recently bought the XPS 13 Plus 9320 from Dell. I got it August 16 so it hasn’t even been a month of ownership. This problem started yesterday when I did a driver update, When I shutdown the laptop, it turns back on in even when the lid is down and this causes the battery to drain when I come back to use it? I contacted Dell and they went through a couple of things and nothing worked. After the factory reset the product. And still this problem occurs. Do I have a defective product, and what do I do?  
XPS 13 Plus 9320, turns on after shutdown