First time grow - having some issues

Hey all, so i'm a first time grower and have spent weeks setting up my grow up and getting everything perfect, however, i'm having a few problems with my seedlings and would really appreciate some experienced guidance

First of all i'll list my setup

-400w MH lamp
-One small internal fan blowing over the plants with another larger fan blowing from the outisde through vent holes (too big to fit in grow house)
-Using enriched cocopeat as grow medium
-Light cycle 18/6
-Seedlings are about 5 days old

So firstly yesterday I noticed a few of my plants started to V (close up) and started doing research, turns out its heat stress, so I increase the distance of the plants from the lights, gave them a watering and turned off the lights to go to bed as they were due their 6 hours of darkness, hoping that the next morning things would be looking slightly better...

So I wake up and the seedlings are still closed but now two out of the four' stems have collapsed as well, I've propped them up to encourage stem strengthening but i'm not sure if that's even enough? I have a feeling I might have possibly over watered them before putting them to bed

Any help or solutions would be very helpful, not quite sure how to proceed as my girls are looking rather fragile and I don't want to act any further in fear of making another wrong move

Post pics and probably too much water

Still hasn't opened up yet and cant stand on its own...

Light may be a little too intense for seedlings. If you're ballast is dimmable turn it all the way down until you're seedlings are strong enough to stand the high intensity of HID lights. It's in the name after all, High Intensity Discharge. Most people I see on here and through my extensive research usually use CFLs or T5's for the first week or two before switching to MH. I use clones so I don't really have personal experience, that's just what I've seen and read. There may be other issues but the light sure isn't helping anything its like taking your new born baby to the beach with no sun screen.

My ballast isn't dimmable unfortunately, what do you think I should do? maybe just expose them to sunlight until they're ready for the HID? I live in South Africa so they'll get a lot of nice direct sunlight...

Just use natural light until they have opened and started sprouting first leaves, then your journey begins under the light ! I hope all goes well, first grow is an awesome experience