Your flight log shows no sign of a remote controller connection problem. And since your Spark did not return home, I can only assume the battery disconnected or was ejected from the aircraft. If that’s the case, you should find your Spark around -38.69255416, 143.1534007. Plug those coordinates into the map app on your mobile phone and look around that exact location.
DJI Care won’t cover it since DJI requires you to send in the drone when replacing it. The DJI warranty could cover it if it’s still under warranty and DJI finds they are at fault for the loss. I suspect that’s not what they are going to conclude though after reviewing your flight log. If you want to reach out to them anyhow, you can open at case here.