Is the white in the seedling a bad sign or is it n...

I looked over your diary and im not seeing any signs of white or light burn on the seedlings?? and your 150W led would have a hard time burning them at 27inches way from the seedling I find. Your can upload photos to the question you ask to pin point any of the things your asking about. The little white tips coming out of the seeds in germination are its tap root and that is 100% normal. Light burn on plants tends to cause the leaves to turn up and get crispy. They can also be albino/bleached if they get to close to the light but then tend to happen to bud sites that stretch high not seedlings. One thing that looks a bit concerning is how wet the medium is, be careful not to over water them. They will get weird deformed leaves as a seedling and .yellow out on new growth. If you want to ask a new question with this extra info if you think something is still wrong we can better address your question. Good Luck and Happy Growing.