Can’t charge watch, so cannot unpair

If you can't access your iPhone or Apple Watch, or if your Apple Watch isn't paired with your iPhone and you need to turn off Activation Lock:

1. On a computer, go to iCloud.com and sign in with your Apple ID. 
2. Go to Find My iPhone.
3. Select All Devices, then click your Apple Watch.
4. Click Erase Apple Watch. Select Next until the device is erased.
5. Click the remove button  next to your Apple Watch.

How are you trying to charge your Watch and what series please.

Had and still have this 2 month old problem of charging issues with AW7 and have learnt how to make a cheap and more convenient way of charging using USB c to USB a adapters

This is what the top participants usually say

but the crack on the back doesn’t souls like it is helping

The Apple Watch automatically enters Power Reserve mode and displays a thermometer icon. If the thermometer bar is filled it means that the Watch is overheated.

 Overheating

If the Watch is displaying the overheating alert screen and you are wearing it, remove it from your wrist immediately and place it in a cool spot. Yes, it’s water resistant, but don’t throw it in a cool liquid because drastic temperature changes are not recommended either! Let it cool down naturally instead. Check it with your fingers. When ready press simultaneously the digital crown and the side button to perform a force reboot.