At the end of the dnf distro-sync did you answer some questions? Questions about some files like /etc/passwd, /etc/shadow, /etc/group, and /etc/gshadow. Those are the files that contain your users, groups, and passwords.
If you can chroot into or simply boot in to console login you can easily re-create users and passwords. Also you might look in /etc and see if you have files like /etc/shadow.rpm.old. If so you could just copy that back to /etc/shadow. You want to check all four of those files.
Hope this helps.