Restored used iPod is still connected to sellers iTunes account

Hi,

My cousin recently bought a used iPod touch 5th generation off of craigslist.

When my cousin got the iPod it had not been reset and the seller didn't remember the password.

My cousin doesn't isn't that great with iTunes stuff so he brought it to me and I restored it for him and gave it to him to set up.

That was yesterday, this evening he called me and said that when setting it up there was an error because the iPod was still linked to a different iTunes.

My cousin can't really contact the seller since he bought it on craigslist and no longer has the sellers information.

I'm not really sure what to do I thought that restoring it would reset things like that.

Any help would be greatly appreciated.