2016 Dell XPS 15 9550 Won't Turn Off

To whom it may concern- 

I have a Dell XPS 15 9550 that has begun displaying one prominent issue: it will not shut down even after I initiate shutdown, both by pressing and holding down the power button, and when I go to the start menu to shut it down. 

About three seconds after I shut my laptop down through both means, it will begin turning on by itself. I thought that at first, it was one of my peripherals or plugged-in devices that was causing the issue- I tested each device one by one, unplugging each until I finally got to my power cord. 

My laptop will only shut down if it is unplugged from the power cord. Otherwise, it will automatically initiate startup on its own if plugged in to a power source. Why is this happening? Should I see if there are any BIOS updates that can fix this issue? This is a fairly new occurence. 

Any help would be appreciated. 

Thank you.