I would agree with Bryce Nesbitt. DO NOT do these steps if all you’re going to do is replace the battery. Having disconnected and reconnected all this stuff, which absolutely was not needed to get the battery out, my touchscreen is no longer working and there’s a weird grid pattern all over the screen, which suggests to me that at least one of the connectors isn’t seated properly, so I’m going to have to do this all over again.
Let me reiterate: DO NOT DO THIS IF ALL YOU WANT IS TO REPLACE THE BATTERY. Skip straight to step 23 where you start work to remove the battery adhesive tab and strips.