if the canes are totally brown, they are goners. Try keeping them watered, and good luck. New soil won't help. Too bad.

I wonder if you took them out of the pot and soaked them overnight in water. I've read that it might help. When they are repotted I would use new good potting soil and keep them out of the high heat area until they recover from the stress. I would keep them well watered.

If they aren't completely brown and crisp, I'd get them wet and put them in filtered shade for a while. You might have to submerge the pots to get the soil mix to absorb water. If they still have life at the base, cut them back some to healthy wood.

Thank you all. I'm optimistic b/c they all still have green canes. I got rid of the yellow leaves and cut them back some, and I'm keeping them well watered. Temperatures have fallen to the 70s, so that should help as well--they look better already.