parent.lock
   session.json
   xulstore.json

On Oct 11, 2021, complete power outage occured while Thunderbird was in the process of updating to Version 91.2.0. The power immediately came back on, the desktop computer restarted but Thunderbird will not start. When trying to start, a small blue circle appears and then disappears. Using Windows 10, on desktop, 64-bit operating system, x64-based processor. It will not start using the shortcut, or clicking on thunderbird.exe in Program Files (x86) > Mozilla Thunderbird, or using Windows-R and typing thunderbird -safe-mode. It is not running in the Task Manager. I did remove the following from the Profiles folders. But it still won't start. parent.lock session.json xulstore.json I don't know if I need to reinstall Thunderbird. I expect some of the Profile folders need repair, but I need help knowing just what to do. There is an extra Thunderbird and Thunderbird Profiles folder in AppData\Roaming\Thunderbird. I'm sending images of the following: C:\Program Files (x86)\Mozilla Thunderbird C:\Users\xxxx\AppData\Roaming\Thunderbird C:\Users\xxxx\AppData\Roaming\Thunderbird\Profiles C:\Users\xxxx\AppData\Roaming\Thunderbird\Thunderbird C:\Users\xxxx\AppData\Roaming\Thunderbird\Thunderbird\Profiles C:\Users\xxxx\AppData\Local\Thunderbird\Profiles I don't want to cause more damage and hoping you can help. Thank you.