My product is on, but the display is black. What should I do?

• Try the following:
  • Make sure the batteries are inserted correctly.
  • Replace the batteries with new ones, or use the optional AC adapter (APT0615Z1-1).
    
    Warning: Make sure to use AC adapter APT0615Z1-1 or damage may occur.
  • If you are using an AC adapter, make sure that it is securely connected to both the wall outlet and the product.
  • Adjust the contrast setting.