My HASSIO was running fine , I updated HACS and one other add-on, and now it appears to start correctly , but lovelace wont launch!!!
Check the log in either the UI or barring that the home-assistant.log file in the ha config directory for errors. A blank screen usually means there’s an error in the Lovelace script somewhere. If none I would take the Lovelace script down to bare bones so it starts displaying again and then add until it stops, last add will contain the problem.