Hey if you run ‘fly logs’ do you see any interesting info? If the logs are cut off, they stream; so you could leave that running and try SSHing again to get some more logs.
Also, check out Tutorial on SSH - there’s a good explanation of what might be going on here. There’s a chance it doesn’t apply for you
If none of that helps get you any further could you share some of your dockerfile if you have one, and your fly.toml?