Plant is too young and small to deal with heat and light on big amounts. It dries out in a second and doesnt have a rootsystem to counter its strong saturation, I would leave it inside till its like 15cm tall, behind glass. Otherwise she takes most of her energy trying to survive rather than putting it into growth. Think about it, it has a single small root right now, which your plant is using everyday, to counter her burn, atleast shes trying.