Does your DS708 still work correctly as is needing updating? If so did you make a backup of the SD card on a clean windows PC? 
 After you have made a backup on your PC, buy a new Sandisk 16GB class 10SD card.
 Make sure you have the DS708 Software Suite installed on your PC, and do not let the program update the saved backup folder on your PC.
Take the New blank SD card and Format.The format type selected (for card used in DS708 )should be FAT32. Eject the SD card, Put the newly formatted card into the SD card reader that comes with your DS708 and plug it into your PC, copy and paste the backup software files saved on your PC to the blank formatted card. Eject the card from PC . Put card in DS708 , power up tool and see if your tool still works as before, if so , save the old card as the backup and try to update the new card in card reader ,plugged into USB port, one car make at a time using the DS708 software suite from your windows PC . If it says there are no updates for this tool, then you are likely already  out of the 1year free update period, or have not registered the tool yet by entering the serial number and register pass word, that you can access on device by clicking setup/help and clicking the square that reads "About" to find the register password. Write it all down or save a picture on your phone.