Seedlings turned brown and heads on couple went black, HELP save the rest

I posted in the New-B forum and no one has responded, sorry I dont mean to multi-thread, just need some major help fast!! This is not my first grow, Ive had a couple succesful, but this is the first time ive had these problems. I have all my babie in rockwool cubes, in a humidity dome, the dome top was knocked off for about 3 hours, after all had sprouted, the past couple days, most of the plants, have totaly drooped, and some even had there heads turn to black, im assuming they are dead, however some still show signs of life, Im trying not to chalk this up as a total loss, and would love to save the rest, Does anyone know what may be causing this???? they are a lowrider feminised breed, if that helps, and the discoloration is not a solid brown, its more of a light browning, all the green has pretty much left this is in the main stalk, not just heads, and the they are not dry at all. they are under about 200 watts of cfl, and only a week old maybe week and 1/2

Nevermind, I found out I had way over watered, when I picked a rockwool cube up and water just poured out the bottom.