Hey does this look like rot to you?
When you transplanted did you bury the stem? It's not good to bury the stem when you transplant if the medium is hundred percent soil, cause if overwatered it will just be waterlogged and the buried stem will rot. That's why it's yellow- way too wet. The roots do not look healthy, it looks like the main problem is overwatering.
Buy a bag of coarse perlite. Mix 1 gallon of your existing soil and 1 gallon of Perlite together in an empty garbage bag, just shake it around until it's mixed up, taking care of not to crush the fragile perlite.
Get a two liter bottle of water or soda and cut it so it's about 8 inches higher or so. This will be your new container.
Fill the bottom 3 inches of the new container with perlite only. Cut a few holes in the bottom of the new container so water can drain out.
Wet the bottom of the container with water so the 3 inches of perlite is moist.
You'll notice when watering the perlite it just pretty much flows right through and drains right at the bottom immediately, that's the beauty of good drainage. It's pretty much impossible to overwater when you have good drainage!
Next put that plant you're holding into the new container and sprinkle the 50-50 soil/perlite mix all around the plant. Only fill it up to the top of your root ball, don't fill it up taller than that.
Thoroughly water the whole entire container until water is coming out the bottom. Then let it sit until the plant gets extremely dry and is starting to barely wilt. This may take a few days or a week.
At this point it will be so dry the root ball will be searching for water. So you should only water the outside edges of your new container. Do not water the center of the container where the root ball is.
Repeat- Water only the edges of the container. This will incentivize the roots to seek out the water at the edges and it will start to grow normally after a few weeks. Because the container is clear you'll be able to see when the new root growth has reached the edges.
Again, don't water the root ball- only water the edges.
Don't water again it until it's completely dry and just starting to wilt. This wet/dry cycle is what will help the plant grow out of its current funk.
Once the roots have reached the edges of the new container it'll be time to transplant into a well drained medium with a lot of perlite.
Again, if you have super good draining medium, it's almost impossible to overwater. This is really important for small container plants.
Hope that helps