Reply To: "White Screen of Death"
It feels like a muddle with the theme config in the database.
You could try removing all themes except GovIntranet and installing the new TwentySeventeen theme and latest version of WordPress. WordPress should then try to default to a theme and will hopefully pick TwentySeventeen.
The latest versions of GovIntranet (4.30+) handle child themes better, so I’d recommend updating theme and plugins.
Please let me know how you get on. Do you have access to phpMyAdmin or similar?