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?

Yeah, it's pretty common for those to get wedged under the plastic, causing the switch to stay stuck and melting the coil and other things. If you put an in line fuse right off the coil with a 2 amp slo blow, if that happens again, it'll just blow the fuse and save things further down the chain.