Can't log in to GUI, can still access via ssh

Hi team.

I've been using AdvancedTomato on my Netgear R7000 for a few months. It is top stuff.

Since installing tomato, I've been logging into the GUI with default credentials - which is either root/<blank> or root/password.

I was doing that thing I shouldn't do, and clicking around to check out the settings. I enabled admin access to the GUI. This forced me to log in as admin/admin. Because i'm an idiot, i unticked the Allow Admin option, in the assumption that i'd be able to go back to...

Can't log in to GUI, can still access via ssh