How did the roots look that were inside the original potting material? Your phal looks dehydrated, perhaps from root loss. The dying arial root could be from low humidity in your growing area. Repotting was a good idea but I think now your 'chid needs a shady, humid spot and some time to regroup. Misting will probably help, just be sure not to get water in the top of the plant which will probably lead to crown rot.

Good luck!