Summarized. Mac user, but not necessarily an Apple fanboy. They don't make 'em like they used to.
iPad 4 Wi-Fi Battery
For me, it was impossible to accomplish this step without first removing the 7 screws from the Logic Board and disconnecting the Logic Board connectors (Wi-Fi, Speaker, Dock/Lightning) at the bottom. Then, I could slide the Logic Board downward just enough to pull free the SIM cable. When reassembling, I attached the 3 antenna connectors first, then the SIM cable, before installing the 7 screws and Logic Board connectors (Wi-Fi, Speaker, Dock/Lightning) at the bottom. Went a bit easier.
This was an ambiguous step. The Dock/Lightning connector and Wi-Fi antenna cable lift off fairly easily, but the Speaker connector cable does not. I ruined the existing Logic Board at this step. Not an emotional event, as I was replacing it, anyway, but showing how the connector looks, lifted out of it’s socket, would have helped. What tool did you use to pull/lift the connector from it’s socket? Prying from under the wires just stressed the wires, and I had to stop that attempt for fear of damaging the connector. Once I ripped the socket from the Logic Board, I was able to pry the two apart with my fingers, and had a better understanding of how to connect the Speaker cable to the replacement Logic Board. Sometimes these connections slide together, sometimes they’re pressed down into a socket connector. Do one when the other was intended, and you ruin things. You fell short, here.