Tried to install the latest BIOS 0805 for my Z370-PLUS [ it's already 0805 but since dates differ between Asus site and the Bios, tried anyway ].
And it tells me ":-) You have aready the latest BIOS".
Fine, normal, after all.
Then for some reasons the Boot Order was changed!
The "Network Stack" has been enabled and could not boot anymore [ "Checking Media presence..." ]
To flash a new BIOS, the net stack is enabled automatically it seems then, in case the BIOS is already the latest, the flash utility doesn't restore the settings - it seems.
So had to fix the boot order.
Please fix your BIOS bugs... [ and still waiting for the WoL bug to be fixed ]