was the fan blowing directly on the plant?
the floro light itself shouldnt of killed the baby from heat.
floros dont really get that hot, at least hot enough to kill it.
this is just a theory, not set in stone
but, maybe the fan was blowing too hard on it and it folded under pressure.
their little stems are very weak, and the slightest pressure in the wrong spot
will fold them over.
there is a bright side, at least it was just a seedling.
i would advise you to only let the fan just slighty move the plants until they are larger and have the stem strenght to with hold more air pressure.
most floros put out a more blue spectrum of light