Are you saying that it installed successfully (the second time), but will not boot?
If something like Fedora does not boot to the GUI, it typically means that something is wrong with the X configuration file (/etc/X11/xorg.conf). When it boots to a command prompt, you have two options of how to log in: Your regular user name, or "root". During install, you were asked for a root password, plus your regular user name and password. Can you log in with either?