Also to add that for anyone who believes in God, and the Bible, it is not hard to understand the concept of a devil, demons, and demonic possession. The Bible is littered with cases similar to Amanda's from the Old Testament to the New Testament.
In the absence of any science-backed explanation for Amanda's strange voices and instant physical strength, I will defer to the Bible and how those demonic cases were conclusively dealt with. There are also contemporary examples as well, depending on where and how you look.
God, the devil, and demons all exist and they all seek to interact with us all, and possibly live in us. Each one of us has the sole authority to decide who we let into our lives.
That is my biggest takeaway from Amanda's story. Thanks, Dan for sharing, and Merry Christmas!