Young plant problem ive never run into before! someone please help.

So this is my 4 week old plant (yes I know it's small this is a outdoor grow and it hasn't been very sunny lately) so this when I wokeup this morning and put her outside she looked healthy and perky about 2 hours later I decided I'd top her (early yes I know but I'm experimenting) and she still look happy. About 3 hours after that I went out and just one of her leafs was blowing around in the wind not supporting itself, folding under the slightest bit of wind and is going dark green\black\purple? Could anyone tell me what might've happened? Its just the middle section of the leaf that's doing it as well the rest is supporting itself fine.

Oh yea I should add I was misting some of my other plants and she got some droplets on the leafs. I saw these and thought it could burn her out in the hot sun so I wiped the leafs down with my sleeve haha. Hopefully didn't have anything thats gonna kill her on my sleeve ay!

Sun may be too hot for the youngins

So the other leafs have started dropping but with yellow spickles instead of blackening wtf!

I know this probably wasn't the best idea but I decided to pull the sick leaf off haha at least now I don't have to look at it