Great guide up until the part where you have to, you know, actually replace the sd card reader. I watched this video to help with that part, but even then they weren’t clear about how they re-attached the sd card reader. What I did was remove the black foam thing and the old sd card reader, then aligned the connector of my new sd card reader with where the connector on the motherboard is. Holding that in place with one thumb, I held the metal part (where the actual slot is) in place with my other thumb (make sure you align it with the two gray pins on the left side) and then use another finger to press down on the ribbon. If you hear and a feel a click you know you did it correctly. Then just place the black foam piece back on and put everything back together :DD
You’re gonna have to do some guesswork about aligning the connector and the ribbon correctly, just don’t press too hard. I didn’t have to. Hope this helps