I abandoned the Coco-only method. I was killing the seedling with too much H2O. 100% my fault. I transplanted to a living soil that I had been nurturing for a few months. It began showing signs of recovering within 12 hours. I buffered and prepped the coco as well as my knowledge allowed. But, I mistakenly believed the notion that coco "can't be over-watered".. maybe after a few weeks in veg that is true. But, 100% false in my situation. Live and learn.