AWS Postgres RDS "storage-full" and not responding. How to bring back online?

I cannot reboot nor stop the DB in AWS console. I cannot connect it with PG Admin. My Java app also print error like this.

org.postgresql.util.PSQLException: 
Connection to xxxx.us-east-1.rds.amazonaws.com: 5432 refused. 
Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.

And And I just realize the storage has been decreasing all the way to zero after the DB is down. I find it really astonishing since the amount of QPS is sparse and low. How can the storage decrease so steadily?

Turns out in this "storage-full" status you cannot connect to the instance. Only thing you can do is to increase storage.

https://aws.amazon.com/premiumsupport/knowledge-center/rds-autoscaling-low-free-storage/

StackExchange Database Administrators Q#286580, answer score: 3