Hi @betsyg ,
Sounds like the battery is failing and needs to be replaced.
Here’s a [https://www.youtube.com/watch?v=DtInQo4ZLNA|video] that shows how to do this.
Replacement batteries are available online. Just search for ''Nokia 8 battery'' to get results for suppliers.
If doing this yourself seems too daunting, contact a reputable, professional mobile phone repair service and ask for a quote