Here's the report I sent to Parrot:
The battery was at 8% when I lifted off. I flew out over the river at about 3 meters height, and began flying down river to the right. Suddenly RTH activated, and the Anafi began flying upward. I wasn’t certain the 20m RTH height would be enough to clear the trees, so I took over and began bringing it down. Simultaneously, I began running toward an opening in the trees near the river. But I stepped into a ditch, and when I had recovered my footing, the screen showed that the Anafi was underwater. I immediately entered river, which was from 300 to 1000mm deep. After a brief search, I realized I could see into the water better with my polarized sunglasses, so I went to the truck to get them. Once I returned, I oriented myself to the last seen position of the Anafi, and was able to discover it in about 500mm of water. The drone was underwater between 10-15 minutes.
I retrieved the Anafi, removed the battery, and began shaking out the water as I headed for the truck. Once at the truck, I removed the microSD card, setting it on the dash board. After draining out as much water as possible, I placed the Anafi and battery in the sun on the dashboard, sitting on a black background. In doing this, I knocked the microSD card into the truck’s ventilation system, and so far, that is where it remains.
I kept the drone and battery in sun, but not on the black cloth, for approximately ten hours. Upon arriving back home, I covered the Anafi and battery in a silk cloth, placed them in a pan, and covered them closely with rice. I left them in the rice for 36 hours.
After 36 hours, I removed them. I plugged the battery into an outlet, at which time it blinked in a pattern, then the single green LED shown bright. But no more LEDs lit up, so it appears that the battery is not holding a charge.
I later plugged the batter into the Anafi, then plugged in the outlet cord. The Anafi fan started, and the blue light began blinking. However, I was was unable to connect the Anafi either to the phone or the Skycontroller 3.
I also tried resetting the battery by holding down the power button for 12 seconds, or until the red LEDs appeared. The red LEDs never appeared, an the battery appears to by only partly functional, but not holding a charge. Since the Anafi is not connecting, possibly it’s transceiver is damaged as well.