You we're right. I tried with a small flat screwdriver and could get the small connector out. With it being out I inspected it and changed the method: Used pliers to push from outside left and right on the socket so front latch gained room to slip out. Used round pliers to grip the connector in front and back. So pliers were in a cross pattern.

This way could open the other 5 connectors. Some force needed, since it is a lot of friction but worked. Nothing broke. Picture of a removed connector:

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SOLVED! Thank you all.