I've reset my password numerous times and it still doesn't work.
Even given the recently provided "bloggeradmin" username, and the standard Google account reset process, some blog owners still cannot access Google Apps to manage their Blogger custom domain published blogs.
We do have one bit of hope. One such problem report, recently forwarded to Google Apps Support, was noted by a Google Apps Engineer with the advice
We identified a recent change which may have affected the password reset flow for some users. We expect it to either be fixed or rolled out shortly.
So, there is some hope for a few unhappy new domain owners. It's possible that this problem has been resolved, with Google Apps now using the new comprehensive Google login screen.