Not sure, can't you get your hands on the receipt to go back to the retailer, or if bought off someone you know ask them to deal??i cant as it is now second hand can it be repaired?
Maybe he paid by credit card or bank card? he could dig out a statement showing the transaction, you should only need proof of purchase not necessarily a receipti just pressed slightly on the back of the panel where the line is and it has now gone maybe its a loose connection somewhere? I bought it off a my mate cause he was stuck for cash i just called him and he cant find the receipt typical hopefully i havent just chucked my money down the drain.