Backing off definitely means incorrect password. I have an 8 digit password on all 3 of my Obi's and do not have a problem.
If you have multiple log in credential for your google account, the log in and password used for the Obi has to be the main one for the google account. Even though you can access your gmail with a secondary user name, you cannot use a secondary log in credential with the Obi.
If you have your own domain through Google Apps the credentials can be your own domain, but still the main one. If you do not have your own domain at Google, the credentials must be the xxxxxx@gmail.com log in.