Taking it inside is not the answer. It may well be browning and appearing dried out because of the rainfall landing in a bad, water-holding soil mix full of peat, instead of grit which would allow the rain to flow through instead of (likely) rotting roots. The tree likes to dry out a lot between waterings and can take lots of sun, but if it's badly potted and wet a lot, that's going to do it in (if it already isn't done for). BTW, if there's a layer of pebbles glued to the top, throw it away (pry it off carefully first). Do set a while tile or something reflective against the pot towards the sun to keep roots from cooking. However, if most of the tree is hard and brown, it's probably been gone a long time - they don't show it til after it's too late. If only little bits are brown you may be ok if you learn how to take care of it properly.