Boot device (USB stick) "did not authenticate"

Well,

now (after disabling Secure boot) it boots, but the promised Wizard will not open/start.

The textual (terminal) boot sequence ends up with options, such as “Single, Multi-…”, etc., out of which none leads to the expected GUI (of any kind).

So, what to do next? (Initially, I just wanted to run NomadBSD in the live mode.)

THANKS.