Root Rot on Zygopetalum Mathina Meadows

[Rhonda Svoboda]

Hello Orchid Growers:
I can't believe what happened to this orchid! It was blooming and growing great until it just...died. I took a look at the root system and was shocked at how rotten it was. I cut off the dead roots and tissue. All I am left with is one small, viable root. I repotted it in a back mix with spagham moss but now I am not sure if that's the best course of action.
Can anyone help me save this orchid?
Thanks,
Rhonda