Restored MacBook keyboard & trackpad with an Upper Case Cable Replacement
I was following another iFixit guide, replacing the Bluetooth module of my MacBook (this was a success), when I discovered that during the disassembly I had caused the failure of the keyboard and trackpad. Guessing that I had somehow damaged the Upper Case Cable, I ordered this part from iFixit and replaced it. A fix that caused me to need another fix (ugh).
I had no issues with the Upper Case Cable replacing. It is, however, an extremely delicate part, involving precise placement and near microscopic ZIF socket release bars. I am just glad none of those broke off.
You really need the spudger tool for this task. It may seem simple, but it's essential. Get it.