Are you sure that your system uses Grub and not systemd-boot which is the default in EnOS’ installer?
From the live session, please post the output of the following commands:
efibootmgr
And also, assuming that /dev/sdc is where your EnOS is installed, mount the system partition and post the content of the fstab file:
sudo mount /dev/sdc2 /mnt
cat /mnt/etc/fstab