Unfortunately it sounds as though you may have over-watered the tree. We have found that the trees can be susceptible to over-watering when they are indoors in lower light conditions and only need watering once every 2-3 weeks. The over-watering would have caused the ‘browning’ symptoms that you described. I would suggest that the best indicator of the moisture in the pot is weight, as a guide we expect the 3 litre pot that we supply the tree in to weigh around 1500g when it has the correct moisture content and should not need any water until about 1000g when 500g (1/2lt) water can be added. During the summer months the trees requirement for water rises as it starts to grow and it is subjected to longer daylight hours.