I saw the video where they are siting at the sunken battle ship location. I am so sorry for him.
Whith luck, disassemble everything and open one side of the motor to dry. The motor will not be damaged.
The control board might be ok also but 50-50 chance.
The batteries most likely scrap.
If it was my wheel, i would have jumped and try to catch before it sank. I know the water is cold but you cold get out.