Updated PHP & critical error with theme

I have updated PHP as requested but now there is a critical error with the Bjorn theme – it says: ‘The theme is installed but incomplete. This theme failed to load properly and was paused within the admin back end’. And the website doesn’t work anymore while dashboard works only in recovery mode.

Can someone assist or suggest what to do with this issue?

The page I need help with: [log in to see the link]