To start, I want to say I’m not certain this is a Fedora issue, it is probably an issue in my boot config or maybe windows (a separate ssd on the same machine runs windows). However, the behavior started after rebooting from the most recent Fedora 33 update, and the install was stable for more than a month, so it is possible Fedora is to blame. I have been booting back and forth between windows 10 and Fedora without issue for weeks, until this issue.
I googled the message (ERROR: Invalid Arch Independent ELF Magic) and saw that it is not a specific fedora problem … it seams that a file from grub got corrupted and is not writable anymore. So a
Sorry, forgot to put in the post that I already reinstalled grub. Upon boot machine still drops into GRUB shell, no boot. I think it’s related to Fedora because it happened during a reboot for an update. BTRFS repair suite was also unable to fix the BTRFS filesystem, seems corrupted.
My best guess at this point is that the Fedora update broke my filesystem and grub can’t find it.