I'm going to go ahead and paste from my post on the Answers section on the website:

I have tried to install Elementary two or three times. At first I did not realize I had to enable GRUB and thought that it had not installed correctly and I erased the partition and tried again. When I finally realized the error of my ways, at the end of the final installation it said: “An attempt to configure apt to install additional packages from the CD failed.” It told me to restart. When I did, white text on a black background scrolled by and I noticed the word “fail’ in red text. If I recall correctly, it had something to do with no data being there. Sounds related to me. When it finally loads up, a text box with the word “guest” above it appears and there is no way to log in to the account I had previously created during installation. In case it’s important, the selection for Elementary OS on the sda 6 partition stayed there between installations.

To be clear, when I say the sda 6 partition stayed there I mean it still showed up on GRUB between installations.

Has anyone else had this problem? I don't know what happened exactly. Does anyone know if I can fix this without trying to install again?

EDIT: Fixed! If you have the same problem check the comments!