I see you are using a DWC bubbler. Your water level may be a little high.
At least your root ball is not soaked, or is it?
One of the problems you may be having is the Rockwool is always soaked with nutrients. Rockwool by design holds water close to the root ball. It even can hold the nutrients from day one, then you add nutrients from day 5 to the day 1 and so on and so on. There are build-ups nutrients in the Rockwool that can turn toxic and make the plant react like it was over watered. (In fact it is) Now your picture may not be exact but I get the idea, thank you.

How big of a piece of Rockwool are you using? Does it ever get a chance to dry out a little?

I hope your plants are still alive.
The light is 1 meter away, that's like 39". That's to far away you are only getting about 300-500 lumens to the plant. There is not enough light reaching the plant. A 400w light should be about 40 centimeters or 16". The closer the better with out getting the canopy to hot and burning leaves. You can get it as far away as 60 centimeters (24ā?) but not farther then that.

How about a few pics of the plant? If it's still around.