I ran into an issue recently with a corrupted installation of Microsoft Directory Synchronization tool for Office 365.
In the past, support would tell us to try running the configuration wizard again and if that failed uninstall the tool and reinstall.
I have multiple databases on my instance of SQL Express.
To remove, run Uninstall a Program.
Select Microsoft SQL Server 2008 R2 (64-bit).
Select the instance to remove. In this case MSONLINE.
Select Features to remove. If it is your only instance, click the Select All button. If you have other instances, select only the features under your database, not the Shared features.
This will remove the instance installed by the Directory Synchronization tool, MSONLINE.
You can then run Directory Synchronization tool installation again and configure.