How to fix grub from rescue mode?

[apparatus]

Try to add a new Qubes OS EFI boot entry:

BIOS Update That Will Break Boot

If you use uefi : get a qubes os media installation. boot to qubes os rescue mode. skip to shell. [shell] : efibootmgr -v -c -u -L "Qubes OS" -l /EFI/qubes/grubx64.efi -d /dev/nvme0n1 -p 1 reboot change -d <which drive?> and -p <which efi partition?>. if you want you can make sure first by issuing efibootmgr -v in dom0

Also check the content of EFI/qubes/grub.conf file, there should be UUID of Qubes OS /boot partition, check that this UUID is the same as your /boot partition UUID in this command output:

blkid