Space can be/is very scarce when it comes to RAM module fitment in the Intel NuCs. Especially double-sided ram modules (chips on both sides of the PCB) can be troublesome (and pictures of the linked RAM module set in your original post, suggest your RAM modules are double-sided.
In my personal experience, the most common issue is when two double-sided modules are installed - there is tension and physical contact between the RAM modules due to the cramped space. It might also be possible that a single double-sided module is in physical contact with something else underneath.
Assuming the module(s) are installed correctly, here is my trobleshooting suggestion (this worked for me with dual double-sided modules in a former NuC): Cut to suitable size, a thin piece of clean, non-conductive plastic. The objective is to insultate the memory chips, while adding as little as possible to overall thickness. Make sure to use plastic that can tolerate at least 90 degrees celsius without melting or deforming. Place this piece of plastic between the module and the PCB beneath (make sure it does NOT interfere with the module slot/socket), and/or between the modules if using a set of two. See if it will boot up now.
I've read people have basic paper tape with some success, but I'd be careful with this as it may not tolerate the level of heat generated by direct contact with the ram modules, and the introduction of adhesive is rather unfortunate.
This is not likely to be supported by Intel, but if you're careful and make sure to use clean, non-conductive plastic - I don't see any reason for this to void any RMA rights in case it doesn't work out.
If this solution works for you, please mark it.
Regarding the compatibility of the RAM, make sure your are using the correct voltage (1.35v) and that the speed is properly set also to be compatible (1600MHz). This information can be checked at BIOS level.
This is important to make sure the NUC is not being forced to work out of its specifications.
Also, test each RAM module in this DIMM slot that is providing you with the issue, disregard if already done.
If you perform the tests above, and the problem persists here you can find the support page to get the RMA on the unit.
Please make sure you add the troubleshooting done so far and also the information provided in this thread.
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