My JL Audio sub is dead. What exactly happened?

So at my wife's request, I hooked up a Roku to my main system. Roku is a device for internet streaming movies and tv. The connection between the Roku and my preamp, a Meridian G68, was a 12 foot optical cable.

The first night, I hook up the Roku and it works perfectly.

The next night, I move some cables around, then I hook up the Roku again, exactly the same way as the previous evening. I get picture but no sound. Weird. I pondering what I might have done wrong when out of the speakers... POP. POP! POP!!!

Uh oh.

I dive for the amps, switch them off. The POPs stop immediately. But...

Now there's a TERRIFYING HIGH PITCHED PULSATING NOISE coming from somewhere in the room. I finally realize it's coming from the sub, a JL Audio Fathom 113. I dart across the room, switch it off.

I stand frozen, savoring the final moments of the fantasy that maybe things aren't that bad.

Here are some questions in no particular order...

1. I suspect the amp in the sub is fried. Does that sound right?

2. Where did those POPs come from? Could a damaged optical cable do it? Or maybe the optical cable wasn't fully seated?

3. Do I really have to ship this 150 pound sub to Florida? Or do you think there's any chance of finding someone local to fix it? (I'm in L.A.) The sub is out of warranty, btw.

4. I tried to take the panel off the rear of the amp (I know, lethal voltages inside) with the thought that maybe I would just bring the amp portion of the sub to someone local to fix. I removed about 12 screws from the rear panel and still it doesn't budge. Why can't I open this thing?

If you have any suggestions, I'm all ears. If not, thanks for reading.

Bryon

P.S. The rest of the system appears to be fine.