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I think there is something going on there, not just a watering problem.
Look at the base of each brown twig. Is there any sort of bug, or a hole where a bug could have entered or exited the plant?
There are insects called borers or girdlers that will eat the plant just under the bark. Right where the maximum flow of water and nutrients goes up and down through the plant. When that flow is interrupted the plant dies from that point out. This sort of damage is called flagging.