Big thank you to Dennis from iFixit EU support :-) The battery I got was definitely defect and after a short diagnosis I received a new one by FedEx Express in 24 hours. All up and running again with my new battery :-)
Just connected the old battery and the Macbook starts. Apparently I got a defective unit….
My MacBook will not power on after the replacement…. I double checked the battery connector, it is correctly snapped in. The diode on the charger connector is lighting up orange. The logic board which is part of the battery assembly is warm… What could be the problem?
For me, both the camera flex cable and the digitizer cable from step 20 came out together. Made me wonder in step 20 where was the cable I needed to release :-)