When you put a laptop to sleep, the recommended method to awaken it, assuming the lid is already open, is to tap the CTRL key a couple of times. This action should awaken the system and at the same time ensure nothing else is done to have any negative affect on any programs or applications that may have been left open prior to be put to sleep. Out of curiosity does this method work? Granted, I understand you're encountering an issue waking the laptop with the lid closed, but I am curious to learn if this works 
I have an XPS 15 9510, and for the life of me, I still haven't figured out a consistent way to wake it up from sleep. The way I use it is to have it go to sleep when I close the lid, and I expect it to wake up when I open the lid.  However, for the life of me, I haven't figured out a consistent way to get it to respond when I open the lid.  Most of the time, it just sits there with no visible response from the computer (screen, keyboard backlight, fans, anything).  I'll try pressing the power button, putting my finger on it to unlock via fingerprint, touch the trackpad, move the mouse, start hitting random keys, etc.  None of those produce an immediate response.  Instead, it turns on a minute or two later (though I've also had it go 5+ minutes without responding). Is there a Dell official way that will get the computer to respond and wake up?  
XPS 15 9510 How to wake up?