Remove all the keycaps shown and the screws under them. You can use a keycap puller, but pulling from the top of the keycaps works too.

There are two screws holding in the battery, which you can access by peeling back the sticker on top. You should note that there is a plastic layer underneath, which should be removed with the top one.

Unplug the battery connector carefully, holding from the plastic part with your trusty fingernails.

First, remove all the screws marked with red and orange, as they are the easiest to unscrew.

Next, there are screws under the rubber feet, their locations are marked with yellow. You don't need a hot air gun or hairdryer to remove the feet, just get something sharp under there and pry it upwards. And don't worry, they will still stick after you've done this (at least a few times).

And finally, If you wish to remove the PCB, you'll need to pull off the rest of the keycaps and unscrew and unplug everything.

To reassemble, just repeat the steps in reverse.