I voted, but then I wasn't sure if I voted the right way so I threw my laptop -really- hard across the room in an attempt at velocity induced time-travel. Strange thing is, it's now got me as not voted at all, so I can only assume it's worked and that the way to ressurect your 40D is to throw it really hard across the room... But then, when I get to thinking (against doctors orders, I might add) I realise that you washed (and did a jolly fine job, say I) your camera a little while ago now. What you'll need is
more speed I recommend throwing it from a moving car, or possibly dropping it from a great height. Dropping it is a good move, seeing as as it's speed approaches the speed of light it'll gain mass, making it heavier, meaning it'll fall faster plus as it approaches the earth gravity gets stronger so it'll go yet quicker. If you want to go back to even before the sand got on the sensor, well, we're talking throwing it out of an aircraft, possibly backwards just to be sure.
Now, I believe I'm needed in classrooms all over the southern USA to sodomise science yet more...