cool, if you try the other radio and it works, then you know for sure the issue is the radio system. If it still does not work, then it has to be the ESC. There are some rare times when a bad ESC will screw up the receiver, so you wont have steering function either.
I didn't realize you had the waterproof version. If you do, you should fill out redcat's warrenty form. I know their detailed description of the waterproof stuff says you cant submerse the electronics in water, but Snow certain shouldn't have hurt anything. They should replace the item, especially if it isn't that old of a truck.