The system does not allow saving and exiting by pressing the F4 key.

When entering the BIOS interface, navigating to the "Security" tab and attempting to disable "Secure Boot", the system does not allow saving and exiting by pressing the F4 key.

For our products, BIOS changes are always saved by pressing F4. There is no built-in option to disable saving. One possible cause: a USB drive was still connected when the customer modified Secure Boot. The BIOS detected this external storage, deemed the configuration environment unsafe, and blocked the BIOS modification.

Solution: Disconnect all external storage devices temporarily while modifying BIOS settings. After completing the changes, follow the normal procedure to continue OS installation.

Additional note: If no operating system is installed on the internal drive, or no hard drive is fitted in the device, the machine will boot directly into the BIOS menu. When entering BIOS this way, the Secure Boot option is greyed out by default and cannot be modified. You must manually trigger BIOS entry by repeatedly pressing Del or ESC during power-on to access the menu where Secure Boot can be edited normally.