The power failure might have corrupted the installation of the Windows client. Your best bet would be to attempt to do a complete uninstall and then a clean install of the application. Here is how to do that:
1. Close all instances of the Windows client.
2. Run the Task Manager and kill any Icenium*.exe processes you find.
3. Go to %localappdata%\Telerik and delete the BlackDragon and Icenium* folders in there.
4. Go to %localappdata%\Apps and delete the 2.0 folder.
and install the Windows client.
Let us know if you are still having issues with the Windows client. Thanks!
Share what you think about AppBuilder and Telerik Platform with us in our feedback portal, so we can become even better!