My plants are dying please help!!

Genetics - Auto Blue Dream
-cabinet - 50*80*150 - Double-door wooden wardrobe covered with aluminum foil
- Flowerpot - 2 11lt cloth flowerpots
-soil was used before, we used it as Biobizz Light mix for 2,5 weeks, then we replaced it with gartengold soil, thinking that it would not work with this soil
-Light - 300 W full spectrum cobled
-I only added an outlet fan as ventilation (8*8pc fan), I made only 8*8 fan-sized holes for the inlet and left it, I will add it if necessary
-Humidity in the 50s

The plant is 3 weeks old, I'm thinking of taking it outside now, I'm in the Mediterranean region, the humidity and sun are good, but the heat scares me.
Inside the cabin, the temperature was hovering around 33 degrees.

root rot, it's doomed sorry. you can bare root it and transplant but you might as well scratch it and start over.

Oh this is so painful for me. I changed the soil I guess that's why it happened, I'm very amateur. R u suggesting that I uproot and plant new plants? Many thanks also.

As an auto you only have a short time to veg the plant. It should be much bigger by now. Get it more light, or start over if possible which would give you a much better result.

I think you're right, I give up.

you dont need to start it in the large pot, you can get away with repotting it once its established. not to sure about biobizz soil, id wait for someone with experiance with useing it