Thanks for joining the NUC community.
I understand your NUC does not boot at all.
Have you tried removing RAM?
If there is a problem with memory, you should get 3 beep code. Please connect headphones or speakers to the audio jack.
If you are able to get those beeps you would know you have a memory compatibility issue, then you need to get compatible memory: Intel® NUC Kit DN2820FYKH — System memory
Thanks allen, I have tried connecting headphone and did not hear any beeps. The lights flash once or twice and nothing comes up on the screen. I am returning the memory and HDD and will get some off the compatibility lists. Can you suggest any that is cheap and definitely works?