For many newer computers (really from Windows 8 and newer), you may need to Disable Secure Boot. You will need to make sure the Boot Mode is changed to Legacy Support/CSM/Legacy Boot or UEFI and Legacy and make sure it is ENABLED.

You will need to make sure that the Secure Boot or UEFI Boot is DISABLED.

After you make the changes to disable Secure Boot or UEFI Boot (and enable Legacy Boot), make sure you save the changes. This is usually done by clicking the F10 key.