In order to fix the dent, we first had to remove the bumper. To do this, we removed 4 plastic pop-rivets from underneath the bumper. They will most likely break when you take them out, so buy replacements at an auto supply store for any that do (you can get 2 for a dollar). Then, We had to remove the lining of the trunk to get access to the nuts and bolts holding the bumper to the frame. We needed a 3/8″ 10MM socket to get to four of the harder to reach bolts at the rear wall of the trunk. There were also a few more bolts at each side of the trunk.

After the plastic rivets and bolts were removed, we were able to pop the bumper out. In order to push out the dent, we had to soften the plastic using a hair dryer on high heat. We did this for about 10 minutes, and I pushed it out by hand with a towel to protect against the hot plastic.

After that, we just put the bumper back on, replaced the pop-rivets, replaced the bolts, and reinserted the trunk lining. The result wasn’t exactly perfect, but it was much better than before.