RNS 316 Admin Page offline after firmware upgrade #25066860

I updated our RNS 316 to the new firmware (6.2.3?) that was released about a week ago. It's been unusable since then. When I open the web admin page it asks for login then goes to a page saying ReadyNAS "Admin Page" is offline. I can ping the RNS. It was also AD-joined; when I try to access a shared folder it asks for login, then denies access to a correct login (including the domain administrator account). I'm told the front display says something like "retry starting" or "retry startup." It was restarted a couple times with no change.

How do I fix it?

Thanks!