I have to use Windows on one of my laptops in order to support a client. It was supposedly safe to upgrade it to Windows 10. I suspect your BIOS was and is fine. What you have is a Windows 10 upgrade nightmare on your hands: Google "windows 10 upgrade black screen with cursor." That's your problem. To be certain, tweak the BIOS to boot from a USB first, then create a USB bootable image of Ubuntu desktop on a different computer. Insert the USB and restart the NUC. Select "Try Ubuntu" rather than install. If that works you problem is the Windows 10 upgrade. Good luck.
Thank you for contacting us. On this particular case, I would like to ask you few questions before we continue with the thread:
*Why are you updating your BIOS? Are you experiencing any issue with your system that pushes you to upgrade the BIOS?
The reason why I ask this first question is because you should update your BIOS with a good reason. The BIOS is very different than drivers, this is not even stored in your HDD. Also, is important to mention if something goes wrong, it could damage your system. If you have been experiencing hardware problems, the BIOS update might be part of the troubleshooting, depending on the situation.
*How did run these updates? UEFI or .exe?