Photos would help, if you have any.
Did you put cinnamon over all the roots, or just on the cut ends? Putting cinnamon all over the roots is not a good idea because it's a strong dessicant, and will actually draw moisture out of the roots. Have you even put cinnamon powder on your tongue? It dries out your tongue, and does the same to the roots! Putting a little bit on the cut ends of the roots is usually more than enough.
How many roots are left on the plant? If there still quite a few nice ones, repotting and placing it in a warm spot out of bright light is enough, until it recovers.
If there are very very few, you need to get it into a somewhat humid enviroment to limit evaporation of water through the leaves, since the plant will have trouble taking up water with it's limited roots.
Get fresh medium, and repot it into the smallest pot the roots will fit into. I had a phal in the same situation as you this past summer (with only 4 very short roots) and I didn't have such pots, so made a pot out of the bottom half of a 0,5 liter water bottle, with plenty of drainage holes in the bottom. I stuck it in a clay pot for stability. Then I put the entire thing in a large transparent bag with some damp sphagnum moss at the bottom for humidity. I left the bag a bit open at the top and stuck it in a shady spot, out of the sun. The large plant looked ridiculous in such a small pot, but it worked! Now the plant currently has about 6-7 new roots growing, and soon I will need to put it into a larger pot. I also kept the plant on the dryish side for a few weeks in the beginning, waiting a bit longer than usual to water. This helps encourage new root growth from what I've seen in the past.