see this topic if you need to chroot for grub restore
sudo su
cryptsetup luksOpen /dev/sdaX crypto ( here volume mapper encrypted )
cryptsetup luksOpen /dev/sdaY swap ( case out encrypted )
mount /dev/mapper/crypto /mnt
mount /dev/sda1 /mnt/boot/efi ( if you need Efi )
mount -t proc proc /mnt/proc
mount -t sysfs sys /mnt/sys
mount -o bind /dev /mnt/dev
mount -t devpts pts /mnt/dev/pts/
chroot /mnt
grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=manjaro --recheck --verbose
efibootmgr -v
sync
exit ( quit chroot )
see also with gparted to add flag esp on partition sda1 ( boot is ok , missing esp )