When I turned on the mini pc for first time I saw a little terminal called UEFI Shell, but previously I connected a USB with Ubuntu Server Installer. Instead of start installation process, the UEFI shell appears every time. Check in BIOS and the USB nor NVME does not appear as boot device :(.
I spend 2 or 3 hours checking what the problem were. Finally, I found a solution (I think): My Ubuntu Server booteable USB was connected in a USB 3 port (the blue one), just connected it in a regular USB port (black ones) and ¡vualá! :)
PD. I will need a fan.
My purchase:
CWWK Firewall 2.5G Server
i5-1235U
6x Intel i226-V 6 LAN
64 Gb RAM
NVMe 256 Gb