Hi,

I had PoP_OS! installed on my SSD in UEFI mode.
Then I've installed KDE Neon, also in UEFI mode.
Both were OK, selectable in refind and running.
Lately I've installed PoP_OS! fresh, but reformated the EFI partition, what deleted the EFI/Neon folder on that partition, and now KDE Neon refuses to properly boot.
How can I re-establish that folder and its contents?

Unfortunately, The latest KDE Neon USB doesn't boot either - turns off the screen in the middle of the boot.

If PoP_OS! successfully boots you can repair Neon installation from it (*some mount commands, chroot and grub-install).
Probably KDE Neon cannot find EFI System Partition during boot, ESP UUID (volume serial number in this case) has changed during format.
So check and modify Neon's /etc/fstab file ("blkid" command will show you UUIDs).
IMO after this fix you should succesfully boot Neon from GRUB menu (installed by PoP_OS!).

* - I'm lazy and prefer this https://www.supergrubdisk.org/super-grub2-disk/ tool which can fire up your distro even if you have only one system on disk and GRUB is damaged or ESP formatted etc.
Burn to USB, boot from it in UEFI mode, select default entry ("Detect and show boot methods"), find and select 'neon GNU/Linux' and then issue "sudo grub-install" command from Konsole.

Check /boot/efi/EFI/neon & /boot/efi/EFI/BOOT folders...

THX!
Editing the /etc/fstab and entering the right UUID of /boot/efi partition did the trick - Neon now boots without problems