What to do if roots are rotten?

[Orchid Whisperer]

I don't know where you are in the USA, but if it's warm where you are, not bone dry (desert), and I you have access to shade outdoors, wrap a wire around the base of the bare root plant, and hang it somewhere shady (light but no sun) where you can reach to water it.

Over the summer, the plant should overcome any fungus problems, grow roots, then you can pot however you want.

Bare roots are totally not a problem for epiphytic orchids (yours is epiphytic; grows on trees).