Hello:
I'm from Argentina and my english is not very good, sorry but the local support don't have idea of nothing.
I buy a POD xt Used yesterday. Them I created my account profile in the Line 6 web and tryn to register my used PODxt have this message.
"ESN could not be verified. Please confirm the supplied USN. ( Error: 523)"
After this, today, I contact with the previous owner and request that he remove the registration from their account. And the problem still yet. :( :( :( :( :( :(