Q: redline through battery

Re "pair" the Apple Watch with your iPhone >  Status icons on Apple Watch

Does the Watch seem to have a good battery life and charging normally or does it die really quickly and oftenly. Also it could mean that you are disconnected from your iPhone and you need to reconnect. The second one is more likely because the logo with the battery is a circle with a number. Could you upload a screenshot.

Hi

It's a phone symbol - it means that your Apple Watch is disconnected from your iPhone.

You do not need to re-pair your Apple Watch - just reconnect.

Check that Bluetooth and Wi-Fi are both enabled on your iPhone and that your iPhone and Apple Watch are close by each other.

Check also that you haven't enabled Airplane Mode on your watch  ( https://help.apple.com/watch/#/apd6e1809c9e )

If they don't reconnect automatically, try restarting both.

Restart your Apple Watch - Apple Support

About Bluetooth and Wi-Fi on Apple Watch - Apple Support