I'm starting to get the feeling that you might've damaged something on the board itself to cause the M.2 not to be recognized as it work's perfectly fine on a M.2 to USB adapter.

Have you made sure that all the slots are not responding to the drive?

There are 3 slots, one is a smaller size, but I tested it on the other 2 and neither can recognize it. Everything else is being recognized though (RAM, WLAN, HDD).

Thanks for your reply

Yeah it’s a main board issue then since it can’t recognize them in either slot and those aren’t on a separate board so I’d contact Alienware for a replacement if the warranty is still on the laptop but if not, I’d buy another computer.