For those still having this problem, I finally got around to fixing it properly.

It turns out that the power and ground cables from the wire loom in the top right corner to the trunk, inside the rubber sleeve, broke over time. I removed one side of the sleeve and repaired the wires, and also added a little bit of extra wire to each one so they don't break again so easily.

Hope that helps anyone else that runs into this problem with the car.