> If I boot from the USB stick (isohybrid image) in Legacy mode then it
> all **appears** to work, installation completes, but then the system
> won't boot.
What kind of boot loader did you install? `grub-efi`, `grub-pc`,
something else?
Does your Debian install's boot fail in exactly the same way if you ask
your firmware to boot using legacy BIOS?
> I don't see how I can opt to either "Always boot using legacy BIOS
> mode" or "Always boot using UEFI".
In my firmware, I can/could choose which boot mode to activate.
So on the Debian side I installed `grub-pc` and on the firmware side
I activated the legacy mode. That made it boot successfully using
legacy BIOS mode.
> How would I "Boot the install using legacy BIOS, then manually change
> the install to use grub-efi", I can't see anywhere in the installation
> process that would allow me to do this.
That's why I said "manually".
Stefan
