The install script has been upgraded a bit, with a better response to errors, and no default password anymore.
Now if for some reason your installation fails, it tells you the SQL query, and the exact error it generated. You can then use this information when asking for help in the forums.
And if you can't change your password (I'm working on re-writing the profile page), you're not stuck with an open b2 where anyone could enter with admin/admin, because your default password is now a random password, generated when you install b2.