Site down following installation

I installed the Kommento package, attempting to upgrade. It took down my website http://www.rossmartin.co.uk
Do you have any ideas what settings you might have changed. I was already on PHP 7.1.25 and Joomla 3.9.1
I have now disabled Kommeno and this made no difference.
I have now restored the site and we are running again. I would like to use Kommento but I am now terrified of trying to install it. Would you be able to assist me?

This section can only be seen by users with a valid subscription.
If you have a valid subscription, please login now

Support is
Online

The support team is online and will be able to answer your inquiries. Please stay calm, follow the rules and do not cross post.

We will attend to you as soon as we can.

Your time
Stack Ideas time