Did something stupid , need advice please

So I rebuilt the carb on my 86? 250 Trail boss and hooked up a jumper box to start and run it. It was running great so I took a little cruise around the yard with the jumper box tied down. Hit a bump, jumper box fell, the leads made contact and immediately the engine quit. Now I have no spark, so obviously I blew something out by shorting the battery leads. Any idea what it could be?