I have a way of illegitamately activating visa gift debit cards, but have no way to cash out, as they are invalid. Is there any way to put them to use?
Are you saying they're invalid because you can't check the balance? When you try to login multiple cards the sites will block your IP. So you can change it and then check. The only way to know for sure if the card is invalid is by calling the customer service number on the back. After you input card info the automated response will be "It appears there is an issue with your card." In that case it's been reported as lost, stolen, or unauthorized and it's pretty much dead.
You would need a passable receipt, with purchase time, store, and everything else to even discuss it with a customer service rep.