Hello Slim_Jim, thanks for contacting us through the Intel Communities. I will try my best to help you resolve your issue.
According to your post, you updated the BIOS of the system to the latest version available and it worked fine afterwards.
The issues started after secure boot was enabled.
We got the following workaround on this behavior but it will be necessary to access the BIOS in order to make some changes on it.
Could you please try removing all devices from the NUC?
You could try disconnecting the battery cable from NUC.
Then, put the BIOS jumper on position 2 and 3 in order to access the BIOS on maintenance mode.
If you are able to access the BIOS please follow these steps:
1. Go to the secure boot options on BIOS
2. Enable secure boot (if disabled)
3. Check on the option that says “Install Intel platform key”
4. Press F10 to save changes and restart the system
There is some important information at the following link that you may want to check.
If the behavior persisted, please contact our customer support department for additional information on replacing your product
Thanks for your help.
I tried to move the jumper to position 2-3, but the NUC booted to the windows desktop.
After shutdown if I press the power button the NUC restarts two or three times in a few seconds and sometimes there is no blue power led at all, but after this it starts with blue led and I can hear the fan spinning, but nothing happens.
If I unplug it and wait, then plug it back, I can get to the windows desktop without the boot screen, but that's all.
I can remember the secure boot and the intel platform key options were checked.
Any other ideas?
Slim_ Jim, could you please try doing a BIOS recovery to the latest BIOS version 0026?
Please follow the instructions provided at this URL http://www.intel.com/support/motherboards/desktop/sb/CS-034524.htm