Hi [NAME] Ee welcome to this free user-to-user Alienware laptop discussion forum.  For OEM parts try Dell Alienware Laptop Notebook Replacement Parts | Parts-People.com.  Dell Alienware 17 R4 Laptop Replacement Parts | Parts-People.com.   They also offer refurbished parts. Try requesting if exchange or repair is an option.  Dell Alienware 17 R4 Power Buttons | Dell Alienware 17 R4 Laptop Parts (parts-people.com).   Replacing ribbon cable socket with locking feature is usually fixed by finding 17 R4 on eBay being sold for parts only. Looking for similar motherboard for parts only is also an option. 
Best place for unique parts.  My laptop was working until i replaced the keyboard.  Hope major damage was not done?  2016 - 17 R4.  After board replace, on button lit up for 1/2 second, then button sort of "sparked" then all went black.  Cheap quess cheap hope is to replace the button unit?  But a more dificult problem I am having is finding a little ribbon cable "lock" or what ever it is called.  Any enlightenment would be greatly appriciated. Thanks, Maka[IMAGE]
Alienware repair guestimate?