Debian 12 installation - installation USB stick boots to grub prompt

[Chris Green <cl@isbd.net>]

This continues from my "Failed Debian 12 install..." thread earlier
today.

I can't get the USB Installation stick to boot into the Debian
installation process when I load it in UEFI mode.  If I boot the USB
stick in UEFI mode it just takes me to the grub prompt.

I suspect that this is why, when I boot from the USB stick in BIOS
compatibility mode the resulting installation doesn't work.

Any ideas what I need to do to get the USB stick to boot properly in
USB mode?

The hardware is a Fujitsu Esprimo Q957 system with a 2Gb NVME disk
drive.  Installation on a quite similar Fujitsu Esprimo Q556 system
goes without a hitch (though that only has SATA drives).

-- 
Chris Green