I understand, it's a horrid sight.

I might need to get an expensive accurate hygrometer to double check my humidity, maybe you're right but I'd be surprised if 60% humidity killed it, especially if it crept up higher for a while after misting, unless not enough misting was done and 60% was the highest it really went. I give mine temporary increases in humidity, which would seem right looking at their habitat.

I definitely wouldn't heat from the bottom and from the top, that would be what is be putting my money on for the cause.