Perhaps similar to Black screen after selecting an option from grub boot menu, but i was using a different graphical theme that worked until rebooting Ubuntu 20.04 after an update. Selecting a graphical boot option only shows a black rectangle. Can i fix it from this grub terminal?
Somehow i got the old theme after leaving the rescue console, but that didn't show any options. Reboot, new theme, advanced Ubuntu with older kernel (5.4.0-34-generic (recovery mode)) is stuck at "Loading initial ramdisk ..." so Ubuntu 16.04 fails to boot 'Loading initial ramdisk' might help.
Power on, F12 on this XPS13, Fedora, brings up the old and working graphical GRUB menu (from the grub cfg in the efi folder). Fedora 32 boots just fine, as does Ubuntu 20.04. I ran the same system update that included grub2 on Fedora 32 and even grub2-mkconfig again, but a normal boot still leads to the broken new palm theme that doesn't even list kernel versions in its advanced menu for Fedora (neither does the old theme, though).