Batteries Exploded in a toy?

My mother in law bought my son a BIG Tonka Fire and Rescue truck from a yard sale. The truck is in excellent condition, but then I got to the battery department to change out the batteries, and there were old batteries already in place that I am guessing had exploded. There is blue slime looking stuff, along with white powder around the springs. I clean every part of what I could see and find, and let it dry a couple of days. I went to put batteries in it to see if it would work, and nothing happened. Will this toy ever work, or is it just a plan truck now with no lights or sounds? I could care less either way. It's just another toy to add to the hundreds he has already. Is there any special way I can clean this toy, or someplace I could take it to have it repaired?