Dendrobium phal leaves yellowing after repot

[estación seca]

Those roots you showed and then cut off were almost all alive. That is what older, healthy roots look like. Now the plant has to struggle to survive. This is what we advised you not to do. Even unpotting and then repotting an orchid in this state damages roots so badly they orchid will often decline severely before it recovers.

The plant's only chance of surviving now is to make a new growth with new roots. That may happen soon, or it may not.

Before it grows, there is a good chance the plant will drop most of the rest of its leaves, and several of the growths will dry up and die, as it tries to supply water to the growing point.

[AsuSayo]

I was waiting for a response, and my impatience got better of me, so the mass root purge...
On the first image, those are both orchid roots, but on the second only the older plant's roots. I cut away a lot on the older plant, but only like 2-3 end on the younger plant.

The roots that I cut does not had sustance, I could push through them with my fingers. If this is not the sign of deadness, then how could I tell when is a root on a dendrobium is dead?

[Dollythehun]

Orchids do nothing fast. They teach patience. Please try to understand, when some of us give our best advise, and the OP keeps looking for an answer they appear to "like better," it can be frustrating for the advise giver.

You've now learned something and that's worth a lot.

[estación seca]

I can't tell when roots are dead unless they are wet, black or dark brown, and smell rotten. With dry roots it is impossible to tell whether they are dead. I never remove roots that don't fall off on their own.

I realize some excellent growers advise cutting off most old roots when repotting. I don't do this.