Some systems has a nasty habit of losing access to the firmware after your Linux installation. A couple of examples
This document is a work-in-progress ...
It is not clear what makes this happen - a lot is pointing to bad implementations of the UEFI specification - in some cases the firmware is hardcoded to load $esp/EFI/boot/bootx64.efi
[wiki1]
Your system will usually be able to boot your installed Linux - only the firmware is not displaying correctly.
Usually you should be able to load the firmware on next reboot by using
$ systemctl reboot --firmware-setup
The first attempt to cure would be to reinstall grub - for an EFI system it goes like this
ESP=$(lsblk -no MOUNTPOINT | grep -e 'efi')
sudo grub-install --trage=x86_64-efi --efi-directory=$ESP bootloader-id=Manjaro --recheck
sudo grub-mkconfig -o /boot/grub/grub.cfg
sudo mkinitcpio -P
Next step is to check with LVFS if your firmware can be updated using Linux
Use https://fwupd.org to get familiar with the Linux Vendor Firmware Service. You can also search the database to verify if your system is supported.
There is no one-size-fits-all answer - the following is a list compiled from Manjaro Forum and the first being from Arch Wiki.
Read the Arch Wiki on UEFI and GRUB [wiki2] [wiki3] [wiki4]
I am listing the possibilities from least to most intrusive action.
su -
- provide the root password when requisted$esp/EFI/Manjaro/grubx64.efi
- rename the file or move it to another location