Keyboard won’t respond in boot menu

I want to smash this thing NitroPC mini nothing but problems, I am trying to boot from a usb drive so I can flash Start9 OS, but the keyboard won’t work, as I turn on NitroPc I keep hitting backspace and that opens up the boot menu but my keyboard dose not let me do anything I am trying to press down arrow and then enter but nothing, and yes my keyboard works just fine on all my other devices.

Can some one help please