Installation of PHP based community site called Nova

No. Absolutely 0% chance. A redirect to the 403 error page is always caused by web server configuration blocking you from accessing the URL. This means any PHP code under that URL is not executed, so there is no way to establish a database connection even if you wanted it to.

That’s what I see too. As to why you see that, I don’t know for sure. I do know that this response is generated by the code from Nova itself. I also see that the server response code is 200 OK, which usually means the code didn’t actually crash.

As to why Nova would return a blank page, I don’t know. I don’t know enough about Nova to answer that question.

But you could try to enable display_errors anyway and see if it provides any useful information: