Even if that were true it would be a manufacturing defect not an installation error unless you grounded out the line somehow. It also could be a faulty electrical outlet. Personally it probably is the service provider not dtv stating that you were at fault. Have them show you proof of what actually happened in written form and pictures with who is accusing you and what they expect. The way of the world is to pass the buck to someone else. More than likely it is a refurb that went south. Don't let them steal your money. Its their burden to prove your at fault.
This is CABL.com posting #351547. Tiny Link: cabl.co/mbDCh