The battery is not charging ?!

Check the charger and the cable and the power outlet and ensure that all are working, and also check for debris lodged in the Lightning socket on the iPhone, and check the charging again.

Chargers and cables can and do fail, and power outlets too.

Try a different and known-good charger and cable if you have or can borrow those, or try your charger and cable with a different iPhone.

If the problems persist, contact Apple Support.

If you’re really using an iPhone 7 on iOS 11, also consider an update to iPS 15, too. There have been various improvements since iOS 11.

Update your iPhone or iPad - Apple Support

• Try a different power source
• Try a different Lightning cable
• Inspect and clean the Lightning port on the bottom of the phone using a bright light and a toothpick

You can do these in any order.