Whats wrong???

Howdy, despite what others are saying, I believe your seedling is suffering from a fungal attack, most likely caused by the plastic cup you placed over the top of it, which caused excessive humidity and possibly suffocation by restricting the air flow around your seedling. Plants need air movement to provide CO2 and to also remove waste gasses from the leaf surfaces. Sad to say, once a seedling gets to the stage as depicted in your photos, there is minimal chance for recovery. Unless you have cuttings/clones, cannabis does not require humid conditions. Hope this helps.... Organoman.

Hello Royalgorillaxx, Your seedling doesn't get enough water to its roots. Add more water and make sure the relative humidity in your growroom is around 60%. If you can't afford a humidifier, put some freshly cleaned wet clothes and towels to hang dry in your growroom. Good luck with your project, I wish you all the best! 👽