This article includes a 1:49 video walkthrough.
Quick answer
You only need the included Allen tool and a butter knife. Loosen the two bolts underneath to slide the lower back off, remove the two bolts on the back so the panel can come out, then pop the panel's three snaps (one in the middle and one on each side) with the butter knife. Install the new panel in reverse: middle snap first, then the sides.
Step by step
From underneath, loosen the two bolts holding the lower back a few turns each. The lower back sits in slots, so it slides forward and off.
Remove the two bolts on the back of the lower back completely, so the panel won't catch on them.
Use a butter knife (or anything with a dull tip) to pop the three snaps: the middle and each side. Prying from the flat area works best.
Install the new panel: snap the middle in first, then each side.
Replace the two bolts and slide the lower back back onto the chair.
Also called: lower back cover, back panel replacement, damaged lower back panel, decorative panel.
Video transcript
Today we're going to quickly take off the lower back to replace the back panel. You're only going to need your Allen tool, and you need to loosen this bolt and this bolt underneath here. You come underneath and just give them a few turns. One, two. Come over to this one. One, two. And it just slides forwards. If you look, it's just slots that hold it on, so it's really easy to take it on and off.
Okay. Next, you've got to get these bolts off the back so that the panel can come out, because right now, if you tried to take the panel out, it's going to hit the bolts on the way out. So just remove these all the way.
Okay. Now that the bolts are off, you need a magic tool, and it's called a butter knife: something with a dull tip. You don't want to cut the fabric while you're prying on this thing. This back panel is held on in three places. There's a snap here in the middle and one on each side, and you simply use the butter knife to pop them off. So come over to the side, go in just a little bit, and pry back. There it is. It popped off. Go to the other side. Pry this off. On this one, I like prying from where it's flat right here, versus the rounded side. I just stick the butter knife down in there, get it underneath, and pop. There you go.
Those are the three snaps that hold it on, and it goes on the exact same way it came off. You put your new back panel on, snap the middle in first, snap one side, snap the other side, put your two screws back in, and it's ready to go back on.