if you're really in single user mode / runlevel 1... passwd should work... Is the system functional other than that? Can you run passwd via sudo as a normal user? "[user@host ~] # sudo passwd"
token manipulation says that *maybe* the actual entry in /etc/shadow is broken? Maybe you can post the contents of the file? You can delete the password from the file by changing
Code:
root:$X$SK5xfLB1ZW:0:0...
to
and saving it.