The operation of the solenoids work like this on a HH- there is no in-line protection, so if a coil locks on, like those bat targets for instance, or whatever, it will do damage and you will blow some stuff up. It was a bad design, but there are ways to protect it, too.
I would look at the daisy chain of non working coils first, if they even are daisy chained, but I would suspect and pull the fuses and check those first.
Which coil for what went bad?