Pro Sites: Revert to free level - Can't access dashboard

I had a site that had previously been upgraded to a Pro Level manually. That expired. The site reverted to the free level correctly and the theme and plugins that were above free were disabled (correct). The odd thing though is that the owner could no longer login to the dashboard. The error was that the page was no longer available. I could access it from the Network side though.

So, it appears something is a bit off.