LOL! Are we talking about the little shriveled plant? If it's in the same soil and nutes as the others, I'd say it's either burning from the lights being too bright or a mutant. If it's a mutant I'd drop another seed because that's real estate that could be used by a healthy grower.Has @InTheShed looked at her?
I'm just a friendly novice compared to Shed, maby he has an idea.