Thank you both for the replies! I am definitely going to let it dry out a bit before I do anything, since it *does* look like the main stem is doing okay. I'm unsure about cutting back those two leaves, since I want it to be able to get enough sun (and they aren't totally 100% dead, just doing very poorly).
I'm also definitely going to let the seller know; I found it on eBay so I suspect there's no chance of a replacement, but I am certainly going to try to nurse it back to health. Any opinions on giving ti a bit of plant food and whether that might help it perk up?