Recently my NUC8i7BEH died and it was replaced by Intel in 2 days. Bravo Intel!
My problem is that I want to setup BIOS for the replaced unit in order to recognize my old M2 SSD which hosts the Windows 10 OS (already installed on the old unit).
In BIOS I'm able to see my M2 SSD in Devices-->SATA, but I cannot see the drive in order to set it as boot drive.
I would start by setting BIOS to default settings: F9 (Y), F10 (Y).
Other possibility is to enter Boot Menu: repeatedly click on F10 when you se the Intel NUC logo. While in the Boot Menu, move the cursor to the Windows Boot Manager and press Enter (if you don't see Windows Boot Manager line, attach image of the Boot Menu to your post)