Will3r, I set up a Lab using the same NUC with the latest BIOS version available and I was able to boot to OpenElec version 4.2.1 from a regular USB device.
I would like to share some pictures I took from the system so you can check the settings I had on it.
Please let me know if you want me to try to boot to this OS using another BIOS configuration.
Regards,
