After upgrading one of my Ubuntu systems to 21.10, it now boots only to the BIOS. It appears to be a UEFI issue which is what I believe in my BIOS is called CSM boot mode which is enabled. In order to boot, I needed to create a USB boot as the DVD I created did not boot properly.
Booting to the Live USB and installing gParted, I can see that there is an EFI partition and the Ubuntu partition but I’m not sure how to repair GRUB from here. I tried installing boot-repair but it fails every time. What do I need to do?