The monitor's Power Button Lockout function is enabled. 

  1. Press and hold the Power button for 10 seconds to unlock the Power button function. 
  2. If the above doesn't work then try a monitor reset. 
    1. Unplug the monitor's power cord and hold down the monitor's power button for 30-60 seconds. 
    2. Plug in the Monitor's power cord
    3. Press power button once