In addition to @flyingcakes post, perhaps if you could boot from your live usb and post the output of the following commands, we would have a better picture of your setup:
sudo parted -l
efibootmgr -v
In case of UEFI system, and if you by this mean that you deleted the EFI system partiton of your EnOS and now you have a new one, then you would need to edit your /etc/fstab an change the UUID of your EFI to match that of the new partition.
Also for chrooting into a system on BTRFS the following post by @dalto should give you some idea: