Some had indidual pieces of equipment that were 'fried' but showed no outward damage -- but if you have a massive stike that takes out "substantially all", then you should see some sign at the point of contact (sometimes the point-of-exit). The screwed-up electronics I've seen don't show outward visible signs. It doesn't take much to cause the stuff to be fried.

What short of the A/C system and what makes you think that's the issue? Normally the pathways are separated into different loops. You said there was a cross-over to the 12V system? I do not believe you should see a frying of the AC system from a properly grounded boat from a normal strike through the mast.

If the boat was at a marina with other boats, and you had a lightning strike that pass an huge overcurrent through the AC system, they you'd have other boats that showed damages; and, the breakers on the dock would probably be fried too.

If the boat had an inverter with some AC circuits on it, then the Inverter (might be) fried?

Having said that, lightning isn't always so predictable in its paths. But I believe that you can have someone carefully look for pathways in and out, if it's lightning that really fried wiring.