In the last picture you posted you can see that your roots are starting to shrivel. When roots do that its either over watering or under watering. In your case i would say over watering. What you should do is check your roots. physically check every single root where it starts at the base of your plant. If it feels even a little bit mushy CUT IT OFF!! If you leave it be all your roots will go mushy and you will definitely die. If you are left with absolutely no roots i would suggest putting it in water culture.. I know it sounds like the exact opposite thing you should do.
If you need to put it in water culture (hopefully not) here is what you do.
1 After you cut off all the roots rinse it under water till all debris is off. (before you cut remember to sterilize your tools)
2 Let the phal sit in a solution of root growing fertilizer for 10 min. the crown of the phal should never touch the water.
3 Rinse the phal again
4 Attach the phal to a spike. You can use the one your flowers were attached to. Make sure when you attach it you dont harm the phal but it should be firm.
5 put the spike with the phal in a honey jar and fill it with water. Water will need to be filled to just under the crown. If there is no "older part" of the plant that can be submerged in the water make sure that the crown just touches the water by 1mm no more no less.
Phal in water culture..
If all goes well that is how it will look like after a few months. A phal in water culture is also less prone to any rot. Well from my experience any way.