Hello Dakodack, if you are getting a three-blink pattern that indicates an issue with the memory you have installed. I would recommend you to check if the modules are firmly seated in the slots. And, try booting with just one module installed at a time (switching between the two slots), as it could be that one of the modules is the problem.
Thanks for your reply.
In fact, I am not getting the three-blink pattern. I think I am getting a pattern that is not part of the error code table (the LED blinks continuously).
Also, I have only one memory module that is part of the Intel compatibility list and I tried several times to switch the memory between each slot => same result.
As I suppose this is a NUC hardware default, I decided to return the product to my reseller and to buy a new one. I will let you know if the problem is solved.