When I go into the BIOS Settings to the 'Boot Sequence' menu item I have : When I start the Laptop with F12 I get the following menu: Boot mode is set to: LEGACY EXTERNAL DEVICES: Secure Boot:Off Now I have the situation, that the laptop boots, when the external DVD with the installation DVD is plugged in, but not when it is plugged out.
To be able to boot from an external DVD I changed the settings in the BIOS. After giving up with a self created USB stick I bought an installation DVD and lo and behold Windows was installed.
I needed several tries to install a Windows 10 on an empty DELL Latitude 7490.
