This message was posted on behalf of Intel Corporation
Based on the information provided above, the next thing to try will be to swap parts, because it seems to be a hardware problem, but it could be the NUC itself, or it could be the SSD.
If you press F10 several times when the NUC is starting up, you should get a boot menu, the SSD should be there.
Did it work fine before?
Do you have the option to use another SSD?
Do you have the option to test the SSD on a different PC?
Maybe there is a PC repair store close to you, and they might be able to do that for you.
Try to restore the BIOS to defaults.
The NUC has 3 years of warranty, so, just to let you know, we can replace it for you as well, you mentioned the vendor will do that for you, but I wanted to let you know about that just in case.
If you are interested in the replacement, please get in contact directly with us through chat, email, phone or online support, you just need to select NUC on product type and you will get those options:
Any questions, please let me know.