My series 5 wont reset

Had this watch been working and paired to your iPhone before this, or is this a brand new Apple Watch? Not sure exactly what you have tried, but if it has been connected to your phone, you can try to unpair and erase the watch (use this link: https://support.apple.com/en-us/HT204568). Erasing it should back it up automatically and then it can restore the backup when you set it up again.

Your mom needs to follow all the steps on this page in order to remove the activation lock that is stopping you from using it;