I recently bought a used John Deere HD75 just to mow my yard. Had never used a hydro before. I made one pass around the yard, trying the controls out. I tried edging my large, deep goldfish pond and got too close. It started in and I wasn't familiar enough with the controls to stop it. It sank in about 3 1/2 feet of water. The water covered most of the mower, but I don't believe it got to the air breather. I managed to extract it with a tractor. Now it won't start. There does not appear to be any water in the oil. Although the engine turns over, as far as I can tell, it's not getting a spark to the plug. How badly have I damaged it? Any suggestions? Will it start once it drys out? Obviously, I'm no professional and I feel pretty stupid. Any suggestions will be greatly appreciated.