Perhaps the water from the car wash got into the wiring for the release mechanism. Potentially it just shorted it out, which would have blown a fuse (hopefully). Only problem with this theory is that I'm pretty sure the trunk release mechanism would be wired through the same fuse as the 'central locking system', and if that blew then none of your locks would be working properly.
What model and year is your car? I checked the fuse diagrams for the 2012 and 2013 NA cars, but perhaps the wiring is different on different models and years.

You may need to pull off your hatch trim to check out whats going on under there.

Otherwise you could always bring it back to a dealership, but if they do find water damage then I doubt they would cover it.

 

I am thinking short as well...cars should be capable of getting wet though so I'd think it should be covered by warranty.

 

Hated issue

I had the same problem with my sport,dealer found some corrosion on one of the wires to the relay... Cleaned it up,problem solved. Hope that might be of help.

john

 

Well here's what happened, I pretty much just let it sit all night, dried out, and it released. Then it got jammed again, thankfully just the latch didn't fully open so It never closed. I had to pry the latch with a screwdriver to release and now it's working fine. It's a 2013 sport.. So I'm sure some water tripped the release and then got stuck when I never opened it? Not too sure but it's working... For now. This is the second time it has happened

 

While it is working you might take it to the dealer and tell them it stopped working a few times when water came into play and have them at least note it and maybe check it. Could find something you haven't noticed. I am glad it is sorted at the moment though!

 

This is why I'm not a huge fan of electronic releases when it comes to trunks/hatches. I'd rather just stick with a lever/handle and a mechanical latch, but oh well.