URGENT: how to debug a broken rack

We have a production rack that is misbehaving and we can’t even do “convox login” anymore. It gives ERROR: invalid login. We don’t use console, we log straight into the rack, and it’s always worked

How do I go about debugging the issue?

The only thing we’ve noticed so far is that there are 50+ EC2 instances, when there are supposed to be only 6.

Please advice!