If your trunk fails to latch when you close it, it could be the receiver. Mine got pushed down somehow, causing a temporarily inexplicably-non-latching trunk when I got my 850 back from u-Haul. (I had them install a trailer hitch.)

Hmm.

After some investigation, I adjusted the receiver loop up (star bolts) and it was once again normal. You have to remove the plastic trim to get to the bolts, but this is trivial.