Did your airstone fail? That would starve the roots of oxygen and look just like overwatering.
Why'd you throw her out? What made you think it was a hopeless case? You'll be amazed what a plant will recover from and how far you can let them slide. I've seen a 5' tall outdoor plant recklessly overferted with miracle grow, then watered to within an inch of it's life in an attempt to flush it, fall over from about 3' up, then pick itself back up in 3 days when the sun came out. Hell my friend used to throw his plants, roots and all into his compost heap after harvesting them, until he noticed they had started growing again!