oops HEAT STRESS is evident cause of what you are associating with nute burn....air flow, move the light further away...and WAHLAH!IMO your issue isnt so much nutrient burn, cause it looks like the plant is enjoying the food in picture number 2. id saheat stress and over watering. when your babies are that small over watering can give you an overall look of a non growing; stunted plant. allow the soil to get dry and WATCH