Just a small addendum; it appears to be because previously I had disabled Legacy Boot and Legacy USB in the BIOS. When I choose F9 to reset to defaults, it is re-enabling these options and this is causing the different boot.
I worked this out by selectively changing stuff in the BIOS on a third one of these until it failed. It failed after these options were enabled.
So is there some way to disable these options via a keyboard shortcut or something once inside the BIOS when I cannot see it?!
I can see the Intel logo, but after pressing F2 the BIOS is invisible. But I am able to press F10 and then Y which shows that the BIOS is responding to keyboard input.
I believe this is because I enabled Legacy Boot and Legacy Device, so if there was some other way to disable these options it would allow me to see the BIOS again.
Thank you for clarifying on that for me, in this case, we can try the following:
- Turn the system off
- Press and hold down the power button. The system emits three short beeps from the PC speaker. You can plug headphones into the front panel audio jack, if available, to hear the beeps.
- After the beeps, release the power button before the 4-second shutdown override.
- The Power Button Menu displays. Options on the menu can vary, depending on the Intel NUC model.
If this does not work, then I suggest a BIOS recovery, you can use the latest BIOS version 0046 to do BIOS recovery, please see BIOS Recovery Update Instructions for Intel® NUC
I hope this can help.