Hi, my 320 Gateway (have ATT Fiber) went out two days ago, or so I thought. It was alternating between a red and white flashing light. ATT ran tests and said it was bad and shipped me a replacement. However, the original one went to a solid white light and is working. The replacement has arrived, still in box. Should I go ahead and replace and return old one or just ship the unopened one back? I think it’s the exact same model. Thanks!