I know this is pretty old; but I will add this in case others find themselves in this position. Using Intel NUC Little Mini PCs, I had the same problem. Some systems have a power button feature where pressing a certain number of times or pressing it for a certain amount of time will allow you to enter the bios. However, those did not work for me either.
The last thing that did work was using a Windows 10 boot USB. And using the repair and recover option when it booted. Once it booted to that; I am able to choose change UEFI settings and that drops me into the bios where I was able to disable fast boot. Fast boot can sometimes be a nightmare on some OS's that don't have the Windows log into your UEFI settings function easily available.
Cheers,
T