I have used this technique everytime when I received dying orchids from friends who asked me to save them.
After clearing the roots, I mount the plant onto dead tree barks (moist) and cover it with some moss and charcoal and spray water daily.
Being orchids, they have a mind of their own. The new vertical environment on the mount helps the tired/inactive plant to become active again in the new environment....i think.
p.s. i am not an expert but sharing through experience.