Clownfish812 Said:
"iPhone 13 battery: But the battery must be new because it's brand new"
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Perhaps this is a Faulty Device":
Note that you have a one-year, out-of-the-box, limited-warranty with this, if purchased from Apple. So, either return this (you have 14 days to do so), or contact Apple Support, seeing if you can get this replaced.
Contact Apple Support:
Note: Phone calls are taking a bit to go through at the moment, due to lots of calls. And that makes sense because with the Coronavirus Pandemic, many are at home at the moment, with much time on their hands to contact Apple. So, just stay on the line, and you will get through :)