Focus 2000 PCM questions?

Hi,

According to the Ford dealership my PCM (powertrain control module) on my 2000 Focus is shot. By shot, I mean when they get no information from it when they hook up their computer to it. I learned this when I had it towed in because the car wouldn’t start.

Is it common for a PCM to self-destruct? It doesn’t seem so because I can’t find anything online about it and it’s never mentioned as a reason a car won’t start.

I also want to know if changing a fuel filter, plug wires, PCV valve and oil could some how result in a blown PCM if done wrong. I made these changes a week before my car wouldn’t start.

Lastly, I now know that a new PCM has to be ordered by the car’s VIN but does it have to be installed by the dealer? Doesn’t it come programmed for the car?

Thanks