Thanks Jake, I hear what you are saying but I definately did edit the config file with the correct db details.
It's working now with some errors. I'm not sure if it was just a matter of the system taking a bit of time to update or my request for help with XF support and they did some magic behind the scenes. If I find out I'll advise here. The errors showing in the logs have to do with "likes". Also with the members drop down list in the navigation which doesn't show members, only showing the line "member_stat.highest_reaction_score" instead of a list of members - but that doesn't seem to show in the logs.