How to deactivate secure boot on ZBook 17 G4

[techroad65]

Hello,

For some reasons, I will need sometimes to boot my Zbook G4 from an usb stick.
When trying to do that, I have the following message:
"Selected boot image did not authenticate".

So I tried to disable the secure boot using the Bios Setup and I saved this new configuration.
After having rebooted the laptop, I noticed that this configuration is not saved : the "Configure Legacy Support and secure boot" option I tried to change before has still the same value: "Legacy Support disabled and secure boot enabled".

Knowing that, I tried to deactivate the "UEFI boot order" but this is not possible because this option is greyed.

The Bios version I am using is : P70 Ver 01.02 06/09/2017

Is there any way to disable secure boot on that machine ?

[techroad65]

Hello,

I finally managed to boot my laptop from an USB stick.

For that I needed to :
- Launch the Bios Setup at computer start.
- « Clear Secure boot Keys » from the secure boot configuration menu.
- Set the « Configure Legacy Support and secure boot » option to "Legacy Support enabled and secure boot disabled ".
- Save this new configuration and power off the laptop.
- Launch again the Bios Setup at computer start.
--> Normally, a 4 digit code is displayed
- Type this code (then enter key) assuming the keyboard configuration is Qwerty
- Check the previously option has been correctly recorded.

After that I was able to boot successfully from my external USB device using UEFI mode.