Have you tried in an incognito (chrome) or private window (firefox, IE)? Usually when I get a 400 error on the GoDaddy site, it's due to caching in the browser itself. Give that a shot and see if you can access it that way.
If not, your only resolution would be to contact phone support or live chat. (Link at top of page.)
I am a GoDaddy End User - Just Like You * Please note that I DO NOT answer private messages. Please ask your question in the proper forum so the answer can assist EVERYONE in the community and not just you. If you contact me via PM for help, I will give you a price quote for my personal services. Thanks! *
Once your issue is resolved, please be sure to come back and click accept for the solution