My Jeep is dead, it wont start?

Ok Jeep Gurus,
My friend has just finished installing a new tranny. But they said they accidentilly arced the positive and negative leads while putting the motor in. So they now have no spark to the spark plugs. What could be the problem? Im not even sure if that would mess anything up in the ignition system?

Its also an 89 4.0 six cyl

they need to check all the fuses, hopefully it's one of them but if not it is possible to fry a computer like that.

That year will have fuseable links. Little harder to tell when you'd smoked on. But anybody handy with a meter should be able to test for juice. Next step is ECU I'd also suggest.