Installation terminating with an "error: grub rescue>"

I ran into some errors when trying to install TrueNAS-SCALE-25.04.2.4 via a USB disk built with Rufus-4.9. I am trying to install the software on a QNAP-TS-879-PRO with an i7 and 16GB of memory.

With or without disks in the system, I get what appears to be a boot error where the display shows eight or nine entries of:

“error: unknown file system.”

followed by:

grub rescue>

I know nothing about Linux or Grub so please help with any idea what I am doing wrong. I’ve tried different USB devices, different versions of Rufus and also a down-level version of TrueNAS with no help.