Apple Watch replacement just overheats on charge

Hey SophieStott,

Thanks for posting here on the Apple Support Communities! This is a place where other Apple users can submit questions or respond to others to help lend a hand.

Since it sounds like your Apple Watch isn't turning on, try the following from If your Apple Watch won't charge or it won't turn on - Apple Support

1. Make sure that you plug the Apple Magnetic Charging Cable or USB-C Magnetic Fast Charging Cable all the way into the USB Power Adapter, then make sure that you plug the adapter all the way into a power outlet.

2. Make sure that you're using the Apple Magnetic Charging Cable or USB-C Magnetic Fast Charging Cable that came with your Apple Watch. 

3. Completely remove any plastic wrap from both sides of the charger. 

4. Make sure that the back of your Apple Watch and the magnetic charger are clean.

5. Position the back of your Apple Watch on the charger. The charger's magnets align your Apple Watch, and you should see a green lightning bolt  on the watch face.

6. If your Apple Watch still won't charge, force it to restart. Press and hold both the side button and Digital Crown for at least 10 seconds, or until you see the Apple logo.

7. Try a different Apple Watch Magnetic Charging Cable or USB-C Magnetic Fast Charging Cable, and a different USB Power Adapter. If your Apple Watch is out of power, you might need to wait a few minutes for the green lightning bolt  to appear after you start charging your device. 

If the same continues, it would be best to reach out to Apple Support for further help.

Take care.

On your Apple Watch open settings go to General scroll to about and then it will give you the information you were looking for the serial number as well as that I EMI number included with the model number.