Logic board does NOT have to be removed. nor the trackpad. in fact 80% of these steps are not required. Maybe 5 years from now when you have perfectly normal looking batteries that are dead, will they be harder to remove, but for now, these computers mostly just need battery removal to get rid of swollen batteries. once you drain the battery, there is little contact left with aluminum.

the only thing under the logic board is the thin plastic piece that runs across. Simply remove all logic board screws or anything that attaches to board from fans down, like speakers, and you can pry up on logic board with plastic Uspudger and remove the battery. I had this done in 15 min first time. Caveat, this is NOT DYI stuff. take it to a shop.

the bluetooth antenna can only go one way. the wifi goes to the one that has two next to each other, closest one to the back of computer. then you have a BT antenna that goes NEXT to it, and it mounts closest to back of computer. The BT that mounts closer to the side, it mounts on the front of the computer. both BT mount on the same side the wifi on the other by itself. Its not the end of the world if you get these wrong, you just won’t get perfect coverage, but you’ll connect. Ive used these antennas on MacBook pros with the screens taken off (because the antennas for them are IN the screen)