It seems that he knew this thread existed and have yet to give his side of story/explaination by ignoring.

Have you PM him to give an explaination here? If 1 week no story from him and yet he still online, I think you can ask direction from Moderator on how to proceed. According to rules,

4. Inform the other party (via PM or otherwise) about your thread here, so he/she has an opportunity to defend himself. An accused party who does not reply within 1 week may then be added to the Trade Zone Black List thread.
Don't worry if you have been blacklisted because you are not available for one week, all you need to do is PM a trade zone moderator to have your name cleared if you have settled you dispute then.

Without the story from both sides, can't judge yet.

It's not con yet without him trying to explain here. However, if the TS was right, it is a con case by hiding the truth about the item in order to sell out the item even though there was no warranty was provided.

Just wait for the accused to speak for himself within 7 days lor. If not can request for Mod help to take suitable action.