does it go back to normal on a power off - on cycle of the screen ?
check the cable attachment is fully in. power cable as well.
from the manual -
• The LCD display is equipped with the ability to self diagnose abnormalities. When the LCD detects a problem, the LED
on the front flashes in a pattern of long and short blinks, depending on the type of problem detected.
• If the LED detects a problem, please refer service to qualified personnel
what is the pattern ?
Then call NEC i guess