I had the same thing happen to me and now its a beautiful door stop.
I spent a few months and a lot of money trying to bring my machine back to life but it died every rebuild. And none of the service centers could figure out what was wrong even though they could duplicate the problem.
I would recommend moving on and buying either a new PB or find an old one for cheap.
Sorry your going through this. BTW is your machine a 400 Prismo? This is the machine that died on me. My 500 seems to be fine.