Okay, this is the frog that you recently got as a replacement for the deceased one, right? First, get rid of the moss (see post below). Second, ditch the undertank heater. That type of heating is not recommended for frogs, it's not natural for them to seek heat on the ground. Replace the uth with overhead dome lighting, which is more natural and safe for the frog. A 10 gallon is too small for an adult Whites as well, but that's not an immediate issue (although it will need prompt upgrading to at least a 20 gallon).
It's probably not eating because it's still getting used to it's environment. That is quite common with newly purchased animals, and the more you handle him, including force feeding, the more reluctant he will be to ever move. Take out the moss, cover 3 sides of the tank and possibly add a few more elevated hiding places to encourage him to climb and behave more like a tree frog. I still recommend placing him in a relatively bare tank, I recommend that with ALL newly purchased herps, as it's much easier to monitor how much they have been eating and eliminating. Just remember that because you don't see him move much, it doesn't mean that he doesn't become active at night. Try not to disturb him, only change the water and do necessary maintenance without handling the frog.
Keep in mind as well that you made a conscious decision to buy the first frog and accept the replacement, knowing that the care at that facility had been sub-par. When you do that, you take the risk of buying unhealthy animals that will only die no matter what you do. The replacement that was given to you may very well be in extremely poor health, especially if the frogs were kept as you describe. Instead of supporting this store in the future, you should take your business else where.
-----
*~~Whitney~~*
Though here at journey's end I lie in darkness buried deep, beyond all towers strong and high, beyond all mountains steep, above all shadows rides the Sun and Stars forever dwell: I will not say the Day is done, nor bid the Stars farewell."