why are these seedlings struggling?

Hi. For the background on these...They are multiple strains, planted 12 and 7 sprouted, have lost one already. They are almost 2 weeks old this fri. They are in a grow box under a floro with plenty of ventilation plus fresh air coming in. I can't figue out if I over-watered or under-watered. It could be under since there have been times when I let the root cubes get fairly dry, not as dry as the empty ones in the pic though. But, then again the leaves look like they are having root rot issues. They are yellow/brownish and looking all crispy and burned. The floro could'nt have done this and the temps are in the upper 80's. Much appreciated for any help?

first ur temps should only be about 74f. next looks like theredry. u should always keep moist. never let seedlingsdry out.also, hows ur water. u should not be using tap water because of clorin. and other dissolved solidsin the water. other than that don't know.

Hmmm ok. I find it hard to tell the difference between moist and saturated with these root cubes. I'll give them some more water and lower the temp, see what happens. Thanks

Check ur humidity it should be between 40-60% humidty helps develop roots and with out root seedling stunt and aventuall start to show defiencies but if u add nutes u kill them or ur ph is wrong should sit it at about 6.4 for soil there about hydro is differnt should be 5.5 I had same prob n it was my humidty tht is often overlooked mite twke a week or so to recover if its humidty and the leaves mite stay like tht but about 2-3 days u should see root thts good even if there is no groth showing

Yeah it was under-watering. There's not much I can do about the humidity but I watered them again and they perked up a bit. Going to see if I can salvage these as the second set of leaves come in. But since the growth has already been stunted it will be slow growing.

no prablembro, I know how it is.peace and happy growing.this time next year u will be a grand master. hehe.

Its too hot and they're dead now. You will have to cool it down for the new seedlings.

Just wanted to update this:
Yall were right when I took these pics it was already too late, not long after they all died. 100 bucks in seeds down the drain I appreciate the feedback though. Thank you.

Give them some nitrogen.