I upgraded to v4 of community surveys and now I have broken the component. 

I get blank screens when I click on my surveys, or 404 errors, and the dashboard doesn't display properly any more. When I went into the backend, I found a migrate button so clicked on it and my surveys displayed in the back end, but still not in the front end. My survey module no longer works (I get a blank screen on the pages where my survey should appear i.e. at the top of my EasyBlog category. When I switched the error reporting on it pointed to the Community Surveys module. 

I have also just checked my database tables, as noticed I no longer have any categories, and there is no category table in the database. 

This is pretty urgent, can you advise me how to fix this?

Kind regards

Mel