Apple Watch is not being paired

I reset my Apple Watch because it had error after that I couldn't pair it with my phone each time it's connected to my mom iCloud although I didn't pair it with her before . My mom tried to remove it from her iCloud . It seems there it is not connected ( we entered her iCloud no devices are there) I tried to pair it again and same error appears ! Every time it's connecting to her phone and saying error in the server ! Please help