ReadyCloud does not allow to reconnect my ReadyNAS (RN10200)

Due to a problem with my NAS RN10200 (sometimes does not swith on) I have had to remove it from readycloud. Now I am trying to reconnect it again but readycloud does not detect it. If I search by serial number I can find it, but I cannot register again.

could anyone help me with this issue?

 

thanks in advance and best regards.