There is a reset button in the back of the device (well a pin hole). Hold a paperclip in the reset pinhole till the Power LED begins to flash (about 10 seconds). Once it has reset, use the search utility to find the device and the default username and password are "admin", leave the password field blank.
I'm having a similar problem and reset per your instructions and keep getting this: Only the administrator can access the Configuration page. Thus I can't format the second drive I just added. Any thought?