I know nothing but did revive one my wife left for dead.
Although not as bad looking as yours it was dry and withered and the leaves where pale almost white.
I simple cut the roots and parts that looked dead hard and crumbly. Soaked it in water and put it in a north facing window. That was Oct 2021
Sorry no early pictures
I then went and bought MiricleGro Ochid food and followed the directions 1/2 strength for the resting period feed every 4 weeks water if it dried out inbetween feedings.
It seldom dried out.
By spring 2022 it was full green and growing , summer I switched to the full strength mix and every 2 weeks. Since then roots are robust , 4 new leave sets and FINALLY a flower stem !
Here is my post , not very detailed and im awful at cataloging photos
So I dont have a before pic because I did not think the Orchid was going to pull through. It was brought home , bloomed out and left for dead by my wife. The leaves where yellowing and withered. That was October 2021. I placed it in the kitchen window NE facing. Bought some Miri cal...
www.gardening-forums.com
Since I am no expert and only have what I learned from my mom,
IF I had your plant , I would cut any hard dead rotted parts down to any signs of life, complete soak and rinse whats left , get some new medium and pot and start a diluted feeding.
Jan 2023