I just read your reply about the roots. Jeeze, if there isnt a single root left than there probably isn't much else you can do. It might very well be his time to go...
And what you noted about the compacted moss, especially when you said it was packed alot in the
center, well, thats a strong indicator of what possibly happened to your orchid. When there is too much media towards the interior of the pot, it provides a place for the media to remain extremely wet and soggy after watering. This alone can rot the roots and the crown. The roots become very brown and mushy and then are open to infection which can further the problem. --This is why some sources advise people to place pure white styrofoam peanuts (that are not made of cornstarch) towards the interior of the pot when repotting. It greatly reduces the amount of media in the center and prevents rot. Others may have other options for media reduction in the center. And also, with such compacted moss, there was probably very limited air circulation allowed around the roots, which further increases the problem of sogginess.
Well, im sorry. you probably know all this already, you just probably didn't realize how packed the moss was until you got in there and inspected. If youre like me, you probably assumed it was fine when you bought it. (Ive done that!!) And ever time we water it, we pack it down even more.--which is why some people stray away from using moss as their media of choice.
Don't let it get ya down. Everything happens for a reason. And I am deffinitly not an expert, but I am sure there are highly professional orchid growers out there that have faced a problem like this when they first started out and now look where they are!
Let me know what happens... goodluck again!