You got a typical big-box Phal. IF it came from a greenhouse the day before, this is truly a "miracle plant". More likely it was warehoused/in transit for weeks. Be that as it may, most Phal. and other species are shipped in sphagnum moss. The moss holds moisture and when storage/shipping can take weeks, that moisture-holding ability keeps the plant alive. If you continue to grow it in moss, and in particular solid pots with moss, you are dealing with a dead plant eventually.
My suggestion would be to take it out of the moss, removing all you can. Put it in a small-mouthed pot than drains completely when watered. Don't put moss, bark, or anything else in this pot. The roots should be completely free of material so that they can dry out quickly and completely. Keep it in the shade with good air movement and mist/water it every-other-day. I couldn't care less whether the moisture covers the leaves or not. Some people think that water on the leaves is death to the plant - I couldn't disagree more. But that's simply my opinion. When you see new root growth and new leaf growth, pot it as you would normally, with a well-draining, orchid mix.
Sunburned leaves will never "heal". There will always be discoloration, from brown to black. It is only cosmetic. When the leaf/leaves finally die and fall away, problem solved.
