With the bottom cover out of the way, you now have access to the internal components of your MacBook. Step Two: Inspect the Inside and Locate the Fan(s)
This iFixit guide shows you how to do that. In addition to the pentalobe screws, you also have to use a suction cup and a guitar pick to get the cover completely off. Now, beginning with the Touch Bar MacBook Pro in 2016 (including the non-Touch Bar models), Apple introduced a new step to the removal of the bottom cover. Some MacBook models also have a couple of small clips that hold the cover in place from the center, but you can carefully just pry up the cover to unclip it. Once you have all the screws removed, you can lift up the bottom cover from the back. Keep track of each screw and where it goes, because some of them are different lengths. Take your P5 pentalobe screwdriver and remove the screws around the perimeter of your MacBook. Flip over your MacBook so that the bottom is face up. This step is pretty much the same for any modern MacBook, except for the newer Touch Bar models (more on that below).