First and most important question, does the BIOS show you the unit?
Discussion
Bios looks "stripped", there no optional section for sata m2, except to boot all sata devices

If you put a LiveCD (or usb) with some distribution (ubuntu for example) it could be that it mounts the unit. maybe it is a matter of the configuration of your OS.
The machine runs currently the Elementary OS, I did connect sata m2 externally to this laptop-it recognized, I even formated the sata m2 drive to ext4, but once connectd sata m2 back to laptop slot, sata m2 was not recognised.
Actually I found newer bios file , but it is in .exe format, does that mean I have to update thebios through windows?
Bios file was here: https://www1.medion.de/downloads/index.pl?op=detail&id=18617&type=treiber&lang=uk
