BuddyPress.org

One thing that can cause the forums to act in this strange way through experience is changing your Database username or password. Have you done this before? If yes, go back to the original credentials, and try again.

And from reading your early steps, it seems you sort of messed around with your files, and FTP, would it be possible to start completely fresh? (new wp-install, bp-install)? To see if it gets working?