I think I found what the problem was here. I am sharing in case it's useful for someone.

From: https://docs.fedoraproject.org/en-US/fedora-coreos/manual-rollbacks/

"Manual Rollbacks

When an update is complete, the previous OS deployment remains on disk. If an update causes issues, you can use it as a fallback. This is a manual operation that requires human intervention and console access."

Fix

What I just quoted to you now is from the same page you linked. You need to access tty1, as I understand it. You can do that with the shortcut Ctrl+Alt+F1.

Hope this helps.

Edit: I didn't see that you knew you needed access to the terminal. I guess the quote I gave at the top wasn't necessary.

Edit 2: Artem gives a good idea about trying to boot into an older kernel. Looking at images of Fedora's GRUB2, it looks like there are options to do that on GRUB. If it doesn't show up, there should be an 'Advanced Options' menu, where you can boot into different kernel versions. I found an image of what Fedora's GRUB might look like WITHOUT an 'Advanced Options' menu

Edit 3: If it seems that entering commands to do a permanent rollback doesn't work, you may have to, for the time being, do a temporary one. According to Fedora's documentation, it says to hold shift during the boot process. Then there will be several entries and you need to choose the right one.