The last thing that you want to do in my opinion with a Vanda, or any orchid for that matter, suffering from rot is to increase moisture surrounding the plant. Sphagnum moss will increase the moisture, misting it often will increase moisture and fertilizer will only increase the stress on the plant.
By getting rid of the rot, you increase survival of the plant. By keep it dry, you promote new root growth. You keep it shaded and out of direct sun in order to conserve what moisture it has left internally.
Good luck and let us hope it survives.
