E-Newsletter "Theme not found"

I had E-Newsletter installed (only used once so far). I went to create a new newsletter and got only an error message "Handwritten theme not found" with no buttons or options.

I deactivated and deleted the plugin, planning to reinstall, but at the WPMUDev Dashboard->Plugins, it shows E-Newsletter with only an Activate option.. which doesn't work, obviously.

I've verified the plugin folder is gone as expected after deleting the plugin, but I can't reinstall to address the "theme not found" issue. Ideas?