Hp elitebook 840 not turning on. charging light blinking between orange & wh

hi i turned off my laptop 3 days ago..and now i am trying to turn it on..only the light that indicates charging is blinking between orange & white. same thing is happening directly on charger and on battery and on both. when i press power button for first time(on charger and battery) power button flashes on for 0.5 sec and turns off and light that indicates charging starts blinking between orange & white.please help me