Apple Watch is locked up

Hi

Follow these steps to erase your locked watch and re-pair it with your iPhone:

• Connect your watch to its charging cable, with power connected.
• Press and hold the side button until you see the Power Off slider.
• Press firmly on the display (do not try to slide the Power Off slider - just press down more firmly than a normal tap) and then tap on Erase all content and settings.
• Re-pair your watch using the Watch app on your iPhone, choosing to Restore from Backup if offered the option.

More information:

Set up your Apple Watch - Apple Support

If you forgot the passcode for your Apple Watch - Apple Support