Installation of KIWI-OEM-ISO using bootable usb by using grub.cfg

We are trying to install SLES15 KIWI-OEM-ISO using grub.cfg , but every time it is entering into the emergency mode. We have tried many different parameters but no change in results.
This is the code we are providing in grub.cfg of USB -
Using this grub.cfg file in Bootable USB trying to install kiwi iso

function load_video {
if [ x$feature_all_video_module = xy ]; then
insmod all_video
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
menuentry ‘Boot from KIWI-ISO’ {
set gfxpayload=auto

insmod search_fs_label

search --no-floppy --set=isopart --label WXDATA

loopback loop ($isopart)/os/SLES15/ CP-SLES15-SP4.x86_64-0.0.1.install.iso
linuxefi (loop)/boot/x86_64/loader/linux install=hd:/os/SLES15/CP-SLES15-SP4.x86_64-0.0.1.install.iso
initrdefi (loop)/boot/x86_64/loader/initrd
configfile /boot/grub2/loopback.cfg
loopback --delete loop

Please help how we can install KIWI iso.

And this is the result we are getting-