Cancel trade, claim refund fee and place negative or neutral feedback - with explanation

Sorry auto thing - ask for an alternative means to sent item that would cost the same amount they paid

Ask the buyer for a non RD address do you can send item or ask CJ or an alternative means to send item. If no response then make comment in your feedback to the buyer

Ingnor prior comment on commercial situations the buyer has to pay for returning the item As a private seller you sold the item believing it to be in working order in fact it is but not to the requirement of the buyer if it works no refund

More than likely they can leave feedback. I would wait for then to do so and then leave feedback on them but remember feedback has to be posted within 45 days of auction ending, If you feel their feedback is unfair you can request Trade Me to withdraw their feedback