What does
efibootmgr -v
return?
If you have an EFI boot entry for EnOS, perhaps you might need to change the boot priority.
If not you would need to arch-chroot to your EnOS system and reinstall the bootloader.
See the following post on how to chroot into a systen on BTRFS:
Adapt the /dev/xxxx part to your actual setup.
Also:
https://discovery.endeavouros.com/system-rescue/repair-a-non-booting-grub/2021/03/