How To Fix Linux (grub) not booting after Firmware update (Bios version F.13) (ubuntu 24.04.1)

[HappHashCat]

Hey everyone, i just wanted to quickly make this post to help anyone who also had issues on their HP spectre x360 laptop with dual booting windows 11 and Linux after a firmware update. I had this happen to me yesterday and it was super frustrating. Very disrespectful of HP to treat us Linux users like garbage, this has to change! anyways, first of all you gotta disable secure boot, this only works if you set an admin password in the bios, reboot and then enter bios setup again and then disable secure boot (you will be prompted to enter a verification code on screen). Now you can still boot into linux, even if the grub boot manager disappears after an update, it's just complicated: you have to press "esc" during bootup, then "f9" once the menu appears and then you will just have one entry for windows boot manager and below there is an option to boot from an efi file. select that one and then navigate to EFI\ubuntu\grubx64.efi and select that one with enter. that way you can still get into Linux. Once you did that you can now install boot-repair.

sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt update
sudo apt install -y boot-repair && boot-repair

then launch boot-repair and choose recommended repair. Let it do it's thing and then you will be prompted to enter a command in windows. (you have to reboot to windows 11 and then launch a command prompt as administrator for this to work.
in my case the command was:

bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi

now reboot your system and you are finally good to go. now on startup you will always see grub boot manager letting you choose between windows or linux. Cheers!