This message was posted on behalf of Intel Corporation
At this point I just wanted to let you know that basically you tried all the possible troubleshoot steps that we recommend, and this problem seems to be related to the NUC itself.
Now, even though the memory RAM seems to be fully compatible, as an option you can use a different stick of RAM, maybe from the other 2 NUCs that are working, and the same with the SSD, just for testing purposes, it might make a difference.
So, the next thing to do will be to replace it, in order to do that, you can check with the place of purchase and based on the warranty policy they have the might be able to replace it, or you can replace it directly with Intel®.
You do have 3 years of warranty on it, and if you are interested in replacing it with Intel® directly, please use the following link, you just need to choose the Intel NUC on product type, and then you can choose between: chat support, phone support, or online support and they will be able to further assist you:
Any questions, please let me know.