I had an Ubuntu Amazon EC2 server, running a few websites, and I left it to have an unattended do-release-upgrade. The server said that a reboot was required. I (tried to reboot) it and it never came up. Since trying to reboot, I have not succeeded in getting it to serve a webpage or shell in to it.
What are my options or next steps to recover? Is there a way to download a disk image and recover from that?