The only thing that you can do now is cancel any bids that are made, as long as time allows, and hope no one bids in the last few seconds.
Should there be a winning bidder at auction close, you will have to explain the situation to the buyer and ask if they will agree to a mutual cancellation, or perhaps some other option - I think it's probably better to ask the buyer what they would like to do rather than refuse outright to sell the item, for example offer it at a lower price due to the faults.
