Looks like crown rot. Is that sphag moss it was potted in? Is the nursery an orchid knowledgeable place?
Water was allowed to collect in the crevices between the leaf and stem and up at the top of the stem.
Unfortunately, you should look at this as a learning opportunity. Use a paper towel or napkin to dry the stem/leaf intersections if you get water in them. But it sounds like the nursery had the orchid for some time from your post. And it is likely they rotted it, if I am getting it right.