Thank you all for replying.
So you're saying that yellow leaf is just a dehydration issue?
I was worried it might be some kind of infection which i need to cut before it reaches the stem.
It's true that it doesn't have a lot of roots, and i did try to contact the seller (no response yet).
But maybe also the photo I've uploaded previously isn't showing the roots very well.
It does have about 5 short roots, few centimeters each, which is not a lot, and i wonder how it got to that state, but i think it can survive with them and grow more.
Here's a photo of the (wet and green) roots when i got it and watered it for the first time:
So you're saying that 10 minutes a day isn't enough, and i should soak the roots for hours?
Are you sure it's ok to water them on the night time? i thought it is better to water only in the morning?
Also, one thing i'm worried about is if that's ok if the axis and the base of the first few leaves is soaked too? i.e. in an effort to submerge all the roots...
I've seen people dip them in a bucket of water submerging the base, but then water can get trapped between the leaves...