[EDIT] I just did this task today, and have added quite a bit of additional description:
- Remove all four pieces of plastic trim from around the trunk:
- There are quite a few quarter turn fasteners holding them in place. Since a screw driver does not really fit the wide, shallow slots properly, be very careful not to slip out of the slots and scratch the plastic trim. Even the slightest scratch really shows on the textured plastic (don't ask me how I know
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- The removal order is front (lower), sides, and rear (upper). Take note of the way the panels fit into each other for ease of replacing them the same way.
- The front trim piece is tricky. There are four large plastic tabs on the front edge which engage with the grill, and the rear edge slides into the slot in the trunk gasket quite a long way. Use a plastic trim removal tool and gently flex and pry the trim away from the grill to release the tabs. I see these tabs broken quite often. If anyone knows the "trick" on this piece I would like to hear it!
- The two side trim pieces (and the front trim piece) slide into a groove under the rubber gasket on the trunk. The upper (rear) trim piece does not; it just nestles beneath the rubber bulb. Note that you don't remove the trunk gasket from the edge of the trunk.
Remove the rubber bulb gaskets where the side panels join the wheel well liners. These have internal metal clips. When replacing them fully engage the clips onto the edge of both plastic pieces. If they aren't fully engaged, which is easy to do, the trim will fall off later and be lost.
- To remove the upper (rear) piece you must first remove the windshield wiper arms, which requires a special puller. Cycle the wipers a few times before removing them to make sure they stop in the lowest position. Put a piece of masking tape on the windshield to mark the outer end of each blade so you can reassemble them in the same position. I don't suggest trying to remove them without the proper puller, if they are tight you will scar the arms.
Remove the cap from the windshield wiper reservoir. If you choose to leave it on the tank, don't forget to carefully feed it back through the hole in the trim when reassembling, otherwise it will be trapped or damaged.
You might ask a helper to hold up the hood while you remove the lower end of the gas struts. (I usually do this alone and briefly rest the end of the gas strut in the groove in the top of the plastic wheel liner while I remove the trim.)
Then you need to gently peel the upper edge of the trim piece out of its plastic channel at the base of the windshield. Start at one end and work towards the other. It will be snug. Note the position so you can put it back the same way. When replacing it, make sure it is aligned in the groove then use a gentle bump with the heel of the palm to seat the trim back into the plastic channel.
- Remove the entire tool kit from inside the trunk (not required, but gets rid of the extra weight for the next few steps). Simply grab the styrofoam liner and lift the entire kit up and out.
- Remove the large black screws from the wide black bracket at the upper front outer edge of the trunk (2@T30). (Don't remove the four self tapping screws just barely visibile inside the front lip of the trunk.)
- Unplug the wiring harness (for the light and power socket) from the front right-hand outer side of the trunk (next to the right headlight).
- Remove the small black screws (8@T20) around the edge of the emergency trunk release assembly on the inside of the trunk.
- Pull up firmly on the trunk to release the four rubber grommets from the pins in the frame. (Note: If one or more of the rubber grommets stay on the car, pull them off the pins and put them back into the recesses on the trunk before reinstallation. It helps to put a dab of silicon grease on the pins to ease reassembly as well as removal the next time.)
- Lift the trunk enough to gain access and unplug the wiring harness from the emergency trunk release assembly.
- Now gently feed the emergency trunk release assembly through the opening and remove it from the trunk while lifting the trunk.
At this point you should be able to remove the trunk from the car and access the battery.
When replacing the trunk, it is important to route all of the trunk release cables the same way they were before. And very important: if you are not careful you can dislodge the little plastic piece in the release mechanism which will disable the electric trunk release. It is exposed and can be inadvertently bumped.
Despite the above, it is not especially difficult. It takes me about ten minutes to remove the trunk and at least twice as long to replace it, with the right tools and having done it before. However there are quite a few steps, it does require some care, and you need the special tool for the wiper arms. I suppose it might be possible to slip the trunk out past the unfastened upper trim piece without removing the wipers, but I haven't tried it.
