Just repeating what others have said.
You do not have a strong enough light source. There is no nectar spoon formation, which happens in too low a light level. Should not kill a plant.
What I believe the reason for the poor condition is the soil mix. It will stay water-logged too long. I have killed a Heli because of that before.
My mixes use very open and airy. 1/2 part lava rock / 1 part sand / 2 parts perlite / 1 part peat moss/ and some dried LFS thrown in.
It may be too late, but I'd change the soil mix ASAP.
My Grow List Updated 9/21/15