If Menu→ Picture : Brightness is set too high, then the problem can occur.
Try this
Using the monitor adjustment button, lower the brightness to a desired value.
1. Press the joystick button at the bottom of the screen.
2. Using the Forward/Backward( ▲ / ▼ ), Left/Right ( ◀ / ▶ ) button, move the joystick to adjust the option.
3. After lowering the brightness, press the joystick button one more time to exit from the Main menu.
This guide was created for all models, so the images or content may be different from your product.