XF 1.5 Redirecting to install page after installation/other big issues

For some reason, it seems like Xenforo didn't properly write the file that locks the install page, and now I'm unable to access my site unless I use incognito mode or a different browser. I've cleared my cookies and cache to no avail, as well as renamed the install directory. Any time I try to enter the directory that Xenforo is in, it takes me back to the install page.

It definitely finished the installation, and I finished importing everything from IPB. Does anyone know a fix for this?

EDIT: Unfortunately, all the avatars failed to import.

EDIT2: All of the usergroups and who was assigned to them also failed to import. Definitely need a fix for this one - we have too many donators to manually reassign the rank to.

EDIT3: Any time I try to add other administrators in the ACP, it says my existing password is not correct. I'm able to sign in just fine and have even changed my password then retried, and activated two step authentication.

EDIT4: File health check turns up everything as being fine. I've already rebuilt cache for everything.
Last edited: