m0useanswered grow question 3 years ago Damping off makes the stem shrivel up and turn black in the area accompanied with a sharp bend, the leaves will also look sad and wilted.
The photo you uploaded as your day 4 update, it is not of your plant like you said in the description, and does not have damping off.
The uploaded photos is of a stem that had snapped.
https://www.marijuanatimes.org/recognizing-and-avoiding-damping-off-of-cannabis-seedlings/
This article has a very classic looking plant that's suffering from damping off.
I find the best way to avoid it across all plants is to use beneficial microbes when watering as a seedlings.
Best option is to pull it and start over, still wait for it to fully die and try not to over water them little ones.
Good Luck!