I believe this is the same procedure for 1998-2005 Passat since the parts are the same.
First of all, my problem was a piece of plastic that had jammed into the latch, which I didn’t find until I had fully removed the latch from the car.
Example 1998-2005 Trunk Latch on Amazon
Volkswagen Genuine VW Lock. Latch. Trunk.
Removing the latch is not too difficult and requires a 10mm socket to remove two nuts that hold it in place. There are also two connections and a wiring harness that needs to be removed.
The switch can be tested with a multi meter.
Of course, as stated above, my problem was a small plastic piece that held it from closing.
I may still need to replace the whole latch and some point. They are not too expensive.
Replacing the trunk latch on a 1998-2005 VW Volkswagen Passat is not difficult and a DIY backyard mechanic job; as always, call a professional if in doubt.
I am unsure where the plastic piece came from as it didn’t look like a piece broke from the latch, and it all worked well enough after getting it out.
Putting it all back together is as easy as the removal; just take your time. I had no issues.