Also just happened to me - Using BIOS Boot menu was able to boot from the Ubuntu disk - this did bring up the Grub boot menu. Tried the sudo update-grub and that still led to the same problem.
Also just happened to me -
Using BIOS Boot menu was able to boot from the Ubuntu disk - this did bring up the Grub boot menu.
Tried the sudo update-grub and that still led to the same problem.