When you start a seed, just use pH adjusted water. You don't need to start feeding until it tells you it's hungry! I don't know how many times I've had to repeat this on this forum.. The first set of leafs that appear are the cotyledons, they are like baby food left there from the plant that made the seed. Imagine that once your plant has grown a little root system and a couple of sets of true (jagged) leafs it is entering the toddler phase. When it runs out of baby food you'll see the cotyledons begin to yellow and whither, this is the first sign of a nitrogen deficiency. Feed your toddler a toddler sized dose of nutrients (like 1/8-1/4 strength of what the bottle recommends), then you start to figure out whether or not to give it straight water or plant food, and how much depending on how your plant reacted to the last feeding. That's why it's best to keep notes of the last time you fed it and how much you gave it.
No matter what, the idea in both soil and soilless mediums is to just make sure the root zone doesn't dry out. The root zone starts about 2-3 inches below the surface. I don't think overwatering killed your plant. You fried it with your aluminum foil and your jumping the gun on feeding.