We would like to know what is the board repair process that we have for Vtech and Top Union: 1) When TU and Vtech ship the board repair back to Shure, what PO prefix they use to send back? 4500**** or 4170*** ?2) Serial Number: Do TU and Vtech ship the board repair back as the same SN in which it was received? Or do CEMs relabel with new S/N ? 3) What do TU and Vtech do if the current board revision is different with what they were received ?