Apple watch 4 cannot setup

I have an apple watch 4 40mm that I bought used. I reset it (the old owner didn't) but now I can't pair it. Every time I try to start the configuration I get the message that an update is available, but immediately after it says that it is impossible to determine the update as I am not connected to the internet. the iphone is connected in both wifi and 4g but fails. will it be because i already have an apple watch on my account? I have been trying since this morning but without success