The Bios update seem to have deleted the EFI boot entry for your EnOS judging by the output of the efibootmgr.
Also:
is the command to install the bootloader for Legacy/MBR system if I am not mistaken. See:
You need this one instead:
grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=enos-grub
See:
Make sure to mount your system partition at /mnt and the ESP at /mnt/boot/efi before arch-chrooting.