I closed my MacBook without first exiting the remote screen sharing session, and it caused the remote computer to get stuck on the Screen Locked screen. But I could still access it over SSH.
What I tried
1. Killing the process. top
showed “screensharing” at 100% CPU, so I tried:
sudo kill -9 {pid}
But it didn’t effect the screen.
2. Restarting screen sharing
sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.screensharing.plist
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.screensharing.plist
3. Restarting or stopping ARDAgent
sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -restart -agent
sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -deactivate -stop
4. Giving up
None of these had any success, so I resorted to a forced reboot.
sudo reboot