Use a Fingbox that's been used elsewhere.

Hi I've been using Fing for a while and thought I'd try a used Fingbox before buying a new one for my main network. The original user didn't disconnect the Fingbox from his account but has now emailed support to have that sorted.
How can I tell if the disconnection has happened ?
The Fingbox currently displays flashing blue semi circles and won't go green at all. I assume this is a sign its not connected to my account ?