Well if you have other plants that are experiencing none of these symptoms and are under the exact same parameters you have two options:
- Damaged roots
- Runt, kill it and put a different plant in its place.
Like others have said and I have learned the hard way I gave up trying to rescue plants if they are that young and are having that many issues I know by day seven or eight if I’m going to even keep the plant.
Hopefully your other plants will continue to thrive sometimes we just hit speed bumps!
Edit - looking at the very first picture in your thread and looking past the picture of the plant in question that other plant in the back corner is not healthy it is experiencing the exact same parameters as the one that you were requesting status help with.
So it is not that the plant is a runt the fact is the plants are all damaged because something’s wrong and I would bet pH with nutrient lock out.