2000 plymouth Neon Brain Box Crash?

So I have a 2000 plymouth Neon, just bought it, and knew it needed a little work because it would do this stutter thing like some part of the power would touch for 1/8 of a second then stop and pulsate. We took it in to a garage and the guys hooked it up to the diagnostic computer and said the cam sensor and the Crankshaft sensor needed to be replaced. They did this, and now the car wont start. They played around with it for a few days and decided that it was the "brain box", or the PCM (computer) that crashed. My dad tells me that they are easy to break when the person working on it doesn't know what they are doing. The car in great condition before, whats the likleyhood of this happening "by itself".