Not an expert but have some experience. If the dead foliage is brown and on the inside of the tree with nice green foliage outside then that’s normal. Like all evergreens foliage does eventually die to be replaced with more. The dead stuff should be loose and easily removed with fingers.
Otherwise keep the tree evenly moist without drying out, ideally in part shade although it is quite adaptable to other lighting, and remember they don’t bud back on old wood. Removing too much foliage on any one branch may cause that branch to give up.