Don’t get me wrong: If rice is all you have, then, by all means, use it.
The problem is corrosion, or contamination by dissolved solids – to be exact. These cause shorts between pins and improper operation of the tiny devices on the board.
Using distilled water, which has an affinity for minerals, helps to remove the contaminants. Once this is done, heat drives off the remaining water. Changing it twice makes sure that the contaminant concentration is very low when the remaining water is boiled off.
Speaking of that; should you be adverse to the use of an oven, you can also use a vacuum chamber. Water boils below room temperature at 0 atm, so just dry it in your standard issue vacuum chamber.
(edit: which is not hard, since, IIRC, CA has a pressure pot. Attach vacuum line from Automotive AC vacuum pump to pressure pot and pump down. Leave for several hours.)
(edit^2: Wow. What started out as a more funny-than-serious post makes me think that this is the way to go. No phone disassembly required. Just vacuum it down and let the water sublimate. It might work even without the distilled water soak, and it can’t hurt. It’ll be way faster than rice. I’m out of town, or I’d help, but any of our mechanically-inclined members should be able to assist you.)
(edit^3: Dunk the thing in distilled water and swirl around before the vacuum chamber. Can only help.)