Hi,
I've got the same problem like described here: https://de.ifixit.com/Antworten/Ansehen/79491/%22err%22+message+on+the+display,+the+answer+is+not+clear
And I solving it the same way. Now I put all parts together and it seems to me that the mechanism of the preview switch unit at the bottom of the mirror box doesn't work correctly or at least I don't get it completely together again.
[image|1942571]
Does this look like it should?
Greetings Sebastian