At power-on or reset, use F2 at the BIOS splash screen to enter BIOS Setup (Visual BIOS (VB)). There, use F9 to reset the BIOS to the factory default settings. If you want to use UEFI (you really don't need to if you are using Windows 7 -- but you must if you built UEFI-based boot media using Rufus or something similar), you can enable it in the Boot Order window on the left-hand side of the main VB scene. Then, use F10 to exit from VB saving of the current BIOS settings. At the BIOS splash screen, use F10 and then select your USB key. It should boot from it then...
Hope this helps,
This message was posted on behalf of Intel Corporation
Thank you very much to N.Scott.Pearson for the comments posted previously.
Besides trying the steps above, if the problem still persists then as an option you can try to use a different USB bootable driver, just to rule out a possible problem with it, also we can try a BIOS update to the latest version of the NUC.
Instructions to do a BIOS update using the F7 method:
And this is the .BIO file needed, version 0042 latest:
Here is the link for Rufus:
NOTE: These links are being offered for your convenience and should not be viewed as an endorsement by Intel of the content, products, or services offered there.
Any further questions, please let me know.