It's worth a shot, but if you were going to dose at a concentration required to kill anything other than flatworms, you shouldn't do it in your main system. I was able to kill AEFW at between 100-500 times the recommended dose for a tank, and at that concentration all the pods immediately expired as well. Not sure what effect if would have on a much larger, arguably more complex animal like the worms you're dealing with. My suspicion is that it likely won't work (flatworms are about as related to the worms you're dealing with as I am to a lizard), but if you're at your wits end there's no reason not to try it.

Ahhh, guess that's why the current readout on the charger didn't change a bit. A motherboard running in water?! Crazy! Just taught me something, thanks!

Didn't see it last night, may give it a few days back in the tank. Will then try to flush the holes out with a syringe to see if dead worm slime comes out, if not it may still be alive. Next step will be flatworm exit, and if that doesn't work, then the rock is coming out for a while...

flatworm exit or any flatworm remover will likely not kill your worm. flatworms have a very thin skin and they easily transmit the FWE across their skin and into their systems, killing them. The worm you have is armored and very thick skinned. I had one of these worms in my system about 8 years ago and it was 2 feet long. My method was removal of the rock it lived in and then chiseling the rock apart to get the worm out (broke the rock into 3 pieces, it was annoying but then so was losing fish/corals to the stupid worm). Letting the rock dry out will take forever as if the rock is quite porous there will still be a lot of moisture in it for the worm to survive. I'd say the hydrogen peroxide/water mix method may be your best bet but if the worm is really holed up in there you will have to wait quite awhile to cycle the rock with the decomposing worm in it before you can return it to your tank.