i just add to the secure boot disabled, since you have a intel+nvidia system you need to use the ibt parameter:
ibt=off
this is where you add it when you boot from usb:
then you have to add it to your installation, to make it permanent, otherwise you will not be able to boot into it either… the best would be to add it from chroot after the installation is finished, just dont reboot and do this:
chroot with:
manjaro-chroot -a
then open this file:
nano /etc/default/grub
and inside this line: GRUB_CMDLINE_LINUX_DEFAULT inside the quotes add this parameter:
ibt=off
dont remove anything, just add it to existing parameters, save the file with ctrl+x, press Y, then enter, and update grub:
update-grub
now reboot