Go to Finder. In the menu bar click Go, select Go to folder, type /etc/ and press Enter. In the opened window find the "nologin" file and delete it. It's fixed.
NO LOGINS: System going down ... stuck and won't shutdown
Go to Finder. In the menu bar click Go, select Go to folder, type /etc/ and press Enter. In the opened window find the "nologin" file and delete it. It's fixed.