1. I'm assuming that you are trying to update BIOS in NUC7ixBNx. I understand that the BIOS updated sucked in some point. In this case, I suggest that you should update BIOS using BIOS Recovery from Power Button Menu Method:
2. Press and hold the Power Button until NUC is powered OFF.
3. Prepare USB stick fully formatted to FAT32 (disable quick format option during format). Format your USB on Windows machine (rather than Linux or MAC). Save the Bios file BN0083.bio on this stick. Insert this USB stick into front USB slot with amber color (NUC should be OFF). You may use also one of the rear USB ports (do not use front blue USB port, since sometime the USB stick is not recognized during boot process).
4. Press and hold Power Button for about 3 seconds. Count 1001, 1002, 1003,1004. Release the Power Button. NUC should reboot into Power Button Menu. You should release the Power Button before 4-sec shut down override or when the Power Button LED changes color from blue to amber.
5. Press F4 and the recovery shall start (it can take up to 30 seconds for messages to appear on the screen). When the recovery finishes, press on Power Button and hold it, until NUC switches OFF. Pull out the power cord. Remove the USB stick.
6. Replace the power cord and press Power Button to switch the computer to ON. Let the NUC fully reboot.