There's only two explanations I can think of for that error. 1) you set a password on the OBi, forgot what it is, and you're now entering the wrong password. It's also possible that your web browser is trying to fill in the field via a saved password function, and it's filling in the wrong password. 2) you're trying to log into the wrong IP address, and some other gizmo on your LAN is responding with that error.
Pick up the phone attached to the OBi and key in ***1 to confirm the IP address it has acquired.
If you haven't disabled OBiTALK provisioning, you should also be able to look at the device on the OBiTALK web portal, on its device page, to see the password you set, and optionally, change it.