I tried to install the latest update (after 2 years of no use) and the update failed. I refreshed the browser and the page would no longer load. Now, the server won't start. What's the best way to get this thing running again for a novice? To further complicate matters, I do not know what the ssh username and password is. (it's not pi/raspberry).
This can be worked around if you initially used an OctoPi image and will probably be your best bet to fix the issue outside of re-flashing.
Once you have SSH access you can run
~/oprint/bin/pip install --force-reinstall --no-cache-dir octoprint
sudo service octoprint start