API deployed to Elasticbeanstalk suddenly stopped working

Hi,

I'm pretty new to AWS. We deployed our node.js app to Elasticbeanstalk, while creating Postgres database on RDS. So all worked fine for few weeks and since yesterday, I suddenly cannot access the service. It does not response. I tried looking at logs on Elasticbeanstalk but it's empty after December 1st.

In Chrome Network inspect, it just says: Failed to load response data. Resource with given identifier does not exist. We were using free tier. I am sure something happened with the start of new month, but don't know what. I guess our plan expired or something like that.

Also, I've tried accessing the environment using ssh (with valid .pem file, it worked before). However, now it says Permission defined

What could be an issue here?

Thanks in advance