Try the following:
Test the NUC without memory or an SSD installed. When you power it up, you should notice the following blinking sequence:
3 blinks (3 beeps)
On-off (1.0 second each) three times, then 2.5-second pause (off).
The pattern repeats until the computer is powered off.
Make sure you are using the correct voltage memory for your Intel NUC.
- Remove and reseat the memory.
- Make sure the contacts on the memory and the socket are clean.
- Check for a faulty memory module by trying the memory in a known good system.
If the Intel NUC has two memory slots:
- Try using just one memory module at a time, swapping it between the upper and lower memory slots.
- Try using memory modules from the same manufacturer with the same part number and speed.
If you do not see this sequence you can test another power supply.
Let me know your findings.