msdn.microsoft.com/en-us/library/windows/hardware/jj128256 Mandatory. No in-line mechanism is provided whereby a user can bypass Secure Boot failures and boot anyway Signature verification override during boot when Secure Boot is enabled is not allowed. A physically present user override is not permitted for UEFI images that fail signature verification during boot. If a user wants to boot an image that does not pass signature verification, they must explicitly disable Secure Boot on the target system.
