UEFI Secure Boot (Unified Extensible Firmware Interface) is the successor of BIOS (Basic Input Output System) and is used in new 64-bit complete computers with Windows 8 and above.
The standard enabled UEFI runs only signed bootloaders for security reason. Therefore, it is not possible to boot the computer from a CD or USB drive, unless the option is disabled.
- Click simultaneously the shortcut Restart + Shift key.
- Click Troubleshoot → Advanced options → Start-up Settings → Restart.
- Click repeatedly the F10 key (BIOS setup), before the “Startup Menu” opens.
- Go to Boot Manager and disable the option Secure Boot.
- Change the UEFI boot order according to the medium you want to boot the computer.
- Save the changes and reboot.