Removing the logic board to replace the screws is absolutely asinine and a COMPLETE waste of time. This is only necessary with 2008 models where they put the screws in the dumbest of places. The only reason to replace the cable is you ripped it or it was damaged by liquid. 99% of the time trackpad replacements occur because it is not tracking or not clicking, and these faults lie with the trackpad - not the cable. So, most of the time, you can replace just the trackpad, meaning no removal of the logic board is necessary.
1) Remove the bottom cover.
2) Remove the screws holding the battery in. They will be either tri wing, or that five pin star knockoff torx BS. Buy both screwdrivers, they're cheap.
3) Take the trackpad cable out CAREFULLY! TS0P sensor is inside this cable, &&^& it up and your laptop will run slow with fans revving high all the time.
4) Remove the four tiny black screws holding the trackpad in with a phillips screwdriver. #000 wiha picofinish is your friend here. These screws are totally viewable, and within reach, with the motherboard screwed inside the computer.
Trackpad will come out.
Follow in reverse and all is fixed. If you remove the logic board to remove the trackpad, I will flog you, and it will hurt almost as much as the wasted 20 minutes of your time. ;)