Anyone have any idea what is causing this? I've looked it up and found that at least for younger saplings. Some Browning can be normal in early spring, but none of the images had nearly this much Brown. There is barely any green left among the needles.
Tree companies also can make mistakes. However, me too. But i'm telling you: it's leaves and branches look nothing like Sequoiadendron giganteum. Find a professional dendrologist (best option) or at least landscape designer or architect, advanced gardener. Find out for sure before taking any action on plant.