I am sorry to hear that have had issues with the NUC DN2820FYKH.
At this point, I recommend resetting BIOS configuration to see if there is something wrong with boot process detecting video signal.
Please make sure you keep using HDMI to HDMI cable, this is recommended by Intel.
Take a look at this link for information about how to reset BIOS on your computer:
Thank you for your help: I could see the bios again with an HDMI to HDMI cable. Then I fixed my OS with a bootable USB stick. If I plug the NUC with an HDMI to DVI cable, then I can no more see the boot sequence... but my OS is working. I guess I had a double problem.
The NUC is the only computer I have not displaying properly the boot sequence if using HDMI to DVI cable. I hope future versions wont have this issue.
loving this Bay Trail so far !
Thank you for your support.