If global-messages-db.sqlite is not accessible for whatever reason Thunderbird will just get stuck on a blank pane screen that doesn't allow you to access Account Settings or any other relevant option. (see example: https://support.mozilla.org/en-US/questions/1379540 )
Checking error console only gives you several "Uncaught TypeError: gFolderDisplay is null" .
My suggestion is that when this happens a specific error message be presented in the error console or popup dialog pointing out that the database file is not accessible or corrupt. It would have saved me a great deal of days I had to spend troubleshooting the problem 😄