boot on USB iso manjaro
open a terminal
and check EFI is ok
inxi -Fxza --no-host
sudo parted -l
sudo efibootmgr -v
test -d /sys/firmware/efi && echo efi || echo bios
then for EFI
sudo manjaro-chroot -a ( type 1 if only one line-0 appears )
grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=manjaro --recheck --verbose
update-grub
efibootmgr -v
exit ( end chroot )
then reboot