I recommend that you try clearing CMOS. If this doesn't work, attempt to install the latest BIOS using the Recovery Method...
Hope this helps,
Tried clearing CMOS, and BIOS recovery. Neither worked.
Got 3 blinks when trying with no memory present.
It seems like processor is halting as some point in the BIOS before the BIOS screen comes up.
Does the NUC board have a serial output?
Anyway contacted Warranty did a few tests for them and no I am returning for replacement.