Glad you recovered your Neo, and it is working! I just flew my Neo over a river yesterday. This was in bright sunlight, with some fairly stout winds; I did 'rocket' mode, and the Neo seemed to lose me after reaching peak height. It drifted toward a shore, and the app indicated the Neo had lost visual contact with me (no kidding?). I quickly switched to full manual mode and successfully flew it back to me, landing on my kayak without issue. The highly reflective water surface and bright sunlight might have 'confused' the AI in the NEO, hence the warnings from DJI not to fly over water. I just ordered a remote control, which I plan to use to control the Neo over water while fishing.
One day ago...tick, tock, tick, tock. No amount of heat nor rice will remove any trapped saltwater from within the drone. Chances are it's just a matter of time before it starts acting funny. I recommend opening the case to clean everything inside. The smart phone repair people with tell you how well the magic rice cure-all works 😂
I also lost mine in the water. Very similar circumstances but beautiful sunny day. Did something very similar. But one thing I'll mention... your float is on the top, VERY likely where the GPS antenna is located. Any object can block those transmissions from satellites. So that definitely wouldn't be helping the situation.
Putting electronic devices in rice only ruins the rice. Use a desiccant (the ones that ship in the box the Neo came in) to pull out the moisture. You lost Wi-Fi range in the boat and that's why it failed.
DJI specifically says not to fly it in the rain or get it wet, it has no waterproofing whatsoever. Newer phones have a nano layer that protects them, seems like DJI should investigate that. But my experience is that the vision system doesn't work well around water.