Why did it stop working after a swim in shallow water?
I went swimming in my 6 ft pool and after taking a few pictures, it stopped working all of a sudden. It says that it's waterproof up to 15 meters so this shouldn't have been a problem for it.
Did you make sure that your lens was secured tightly to your camera? Is it not turning on at all? I would refer to the troubleshooting page to see some quick solutions that might solve your problem. Apparently this is a common problem with this specific camera, however, if the camera is not turning on at all, I placed it in a bag of rice for a few days, then gently blow dried the camera and it turned back on! Hopefully this helps and I wasn't entirely lucky. Good luck bro!
The O-rings need to greased (first cleaned), before each use, like those around the battery door, and the lens mount, or the risk for water ingress is huge!