Error: return "Login Incorrect" after enter username without asking password

We got this issue on RHEL 7.4 ( Maipo ).

We tried many user, same issue: return "Login Incorrect" after enter username without asking password

Tried to boot in GRUB2, follow this KB
https://www.redhat.com/sysadmin/recover-root-passwd
for resetting root password but GOT error:
passwd: authentication token manipulation error

Pls help us