Need help plants look burnt

Sorry if this is a little long. I started a few GSC & SSH 5 weeks ago. I made the initial mistake of starting them off in a solo cup cut to about 2 inches tall and I definitely over watered them. When I realized my mistake I transplanted them into a full size solo cup and would let them dry out completely before re watering. After that I germinated a few more to see if I had better results using a full size solo cup and making sure not to over water only watering every 5 days or so once dry. The first set of pics are the first ones that I are 5 weeks old now. I transplanted them into the full size solo 3 weeks ago hoping they would recover. The second set of pictures are the newer ones. They are 3 weeks old. I made sure not to over water only watering when dry every 5 days or so and misting with a small spray bottle morning and night. I'm using Bio 365 Bio start soil. Water is PH at 6.3 run off is 6.8. Temp is 77 60% humidity 700 co2 level im using an AC infinity750 watt led light I had it at 40% and it was 18 inches above plants and thought maybe that was too much so this morning I raised it to 30 inches and lowered it to 20% since i didnt know what else could be causing the problem. I have plenty of drainage holes on sides and bottom of the cups. I know the initial mistake was over watering but figured they would have bounced back by now and the new ones would be good but they are starting to show brown spots on the tips and slowed growing and the older ones keep looking worse. I can't figure out what it is. Was the light to bright and too close. Sorry if this post is a little scattered. Any input would be greatly appreciated.

Honestly, I would do some research and start over..
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Yes to your question about lights, (could be other factors at play too) but agree w/ Dan‘s comment above.
start over, do it better, and you’ll have bigger, healthier plants in 2 weeks. Good luck.

I would start over..........after doing substantial research.
Good luck and welcome to RIU.

I'll give you a head start. Your soil is to hot. Mix that soil you got, 1 part soil 3 parts coco in a solo cup, then dig out a shot glass sized hole in the middle of the cup and pack with just coco. Plant your seed there and let the seed grow before blasting it with food.

Or plant the seed in a rock wool cube and set the cube one top the cup and wait for the root to do their thing.... Cheaper than a bag of coco

I see you made some mistakes at the start, but you're on the right track. Those brown spots could be from over-fertilizing or pH issues. Try lowering your water pH to 5.8-6.0 and see if that helps.

Remeber to keep an eye on the temperature (like soil temperature that was mentioned) and humidity. It makes a huge diference to plant health. Hang in there, good luck!

Thanks for the replies. I have been doing research i guess just not enought lol. I was considering using a cube to start it. The guy that sold me everything told me this soil would be fine to start the plants in but I was thinking the same thing that the soil may be too hot to start them in.