Seedlings come with a 14 days supply of nutrients within. They don't need to be fed. Doing so will likely burn it if not kill it completely. Seedlings have no roots. They begin with a tap root the burrows deep into the soil. From there branches of actual roots begin to emerge from the tap root and they spread out all over the soil in search of food and water and oxygen. This is why you don't see much above soil growth in the beginning, and why most new growers think something is wrong, when actually, everything is acting as it should. Feeding shouldn't begin until roots are established, unless you have a hot soil like Ocean Forest or Happy Frog, then you won't need to feed for up to 60 days.
pH of whatever water or nutrient mix is vitally important to your success or failure. Maintaining a consistent pH anywhere between 5.8 and 6.5 is important because at a slightly acidic pH it makes the elements in the soil dissolve enough to where the plant can take them up and flourish.
And remember, seedlings like soil on the dry side. Less is more. You never saturate your seedlings soil. By doing that you load the soil full of water which displaces and doesn't allow oxygen to penetrate the soil, and your seedlings suffocate and will either get root rot, or just die from suffocation, or both.
Your seedling might survive depending on just how much water and fertilizer you added. I don't know that info so i can't say one way or another if it will live or not. There is a shit load of knowledge that goes into growing marijuana to a successful conclusion. It's amazing to me how many people i see on here that just crack a seed with no knowledge what so ever. There are a lot of great resources out there where you can learn. Seedsman and Jorge Cervantes partnered up to make a very detailed and comprehensive grow guide PDF that i think you should seek out. You can reference any topic you lack experience in, and they will tell you the straight dope man. Seedsman is a seed selling hub out of England i think. Seedsman.com