If your other NUCs are not also FY NUCs, their power adapters are not going to work. All other NUCs utilize a power adapter that generates 19V. The power adapter for the FY NUC, on the other hand, only generates 12V. So, my first question to you is, are you testing with the right power adapter? Look at them closely and make sure you are using (the) one that outputs 12V.
People complain about the forms service not working all the time. Most failures are transient, so just try again. If it is the weekend, you may have to wait until Monday for it to work. There are other alternatives. Here are pages providing contact information by geography:
I recommend phoning them directly. Through the above links, you can usually get to ICS folks that speak your language. You can also use the Intel Customer Support Chat Service, but it is offered in English only and is subject to office hours (9-5 M-F) in Pacific time zone.
Hope this helps,
Thank you for your answer.
Unfortunately it didn't help. The PSU is definitely 12V and works fine with my other NUCs.
I even bought a new one just to make sure, the result is the same.
After dozens of reboots it now boots up occasionally.
But now my USB Ethernet adapter doesn't work. Tried it on all ports, I also tried it on my other NUCs. Everything's fine there, it's just this one causing problems.
This is particularly annoying since this is supposed to be my UTM.
I was perfectly satisfied with it until a couple of days ago.