Dry looks most likely. Sometimes a small pot can get dry in just a few hours in a heated room.
Appears to be planted in a cup? Does it have drainage holes to allow excess water to drain away? It takes a little longer but trees can also drown if the soil is too wet. Symptoms of both over and under watering are similar so only your knowledge of conditions over the past few weeks and current state can decide which is more likely.
BTW, don't feel too bad if this tree does not make it. You will have joined a very long list of people that tried but did not succeed first time.