Hello,I am the person that will be helping you today.
What is the problem that you are having specifically with the registration? Are you connected wirelessly, yet?
I will be standing by, looking forward to your response.
Do you think it's a problem with the password?
Yes, that is the correct password.
So, the device is online and all. Are you able to navigate to websites on the Kindle?
It may be an issue with faulted DNS. Please, unplug the power to your modem & router if you have one, turn the Kindle off and on, and attempt to register once more. Was there any change?