My watch only shows time and a red lightening bolt and will not reset?

I did not charge my Nike watch for a week

I charged it overnight last night

My display is in Power Save Mode and I have tried holding down the side button and both the crown and side button (off the charger) and cannot get the watch to restart.

Hi

Apple Watch displays the time and a lightning bolt (and cannot be used for any other functions) when it has entered into Power Reserve mode, which happens automatically when the battery reaches a low charge level or when it is enabled manually.

You may need to charge your Apple Watch before it can be restarted.

To turn off Power Reserve mode, restart your Apple Watch: press and hold the side button until you see the Apple logo.

More information:

Check your battery and charge your Apple Watch - Apple Support

If your Apple Watch won't charge or it won't turn on - Apple Support