Chosen Solution
I have replaced the lighning connector assembly of my iphone 7 with the products and manuals of ifixit two times. After the repair I check if the phone works and it does kind off, I can choose my language country and wifi but after that if I want to continue setting up my device it shows: device unknown. Both of the times I had this exact same problem. Does anyone know the solution I have started the phone with sim card without and while charging and without but I don’t know what to do anymore.
Try to connect the device to a computer and use iTunes to restore the iPhone.