I’m very curious about SSD failures over time. Are there are any stats out there? I’m talking about the high quality NAND used in the likes of Apple SSDs and not USB/SD-card failures.

A step is entirely missing here – removing the right speaker cable connection from the logic board and also removing the right speaker casing (all the pictures below show it already having been removed). You actually don't need to entirely remove the right speaker to get the logic board out but you will need to remove its screws and lift it slightly. And you will need to remove its plug from the motherboard but that's not hard and it looks identical to the left speaker plug/socket.

You will have to reroute the sata cable beneath too. The drive tray will not simply lift out.