we reinstalled wordpress and the theme from scratch and the site loads correctly now.
thanks for all your help!
thank you but it did not work.
we deleted the theme and uploaded the new Version: 4.5.4
I’ve included our FTP login details if you wanted to take a look. A wp login was also provided in the previous reply.
we had tested with another theme, changed it to “twentynineteen” and we were able to login to wordpress dashboard.