What I would do is spin up a new droplet and follow Move a Discourse site to another VPS with rsync.
But I guess you don’t have your /var/discourse anymore unless you made another backup before you restored the one you found?
So spin up a new droplet, copy your app.yml and restore yesterday’s backup from S3. This is what to do.
Also, what’s your docker version? I had a rebuild fail with an error that looks like this (I’ll track down that topic when I get to my laptop).