HP ENVY Sleekbook Will Not Power On ' Boot Up

With the HP ENVY Sleekbook charger plugged in, charging port light lit orange, and power button pressed & released.
Power button lights up as white, WiFi button lights as orange, after about 3 seconds charging port light changes from orange to white for about half second, then power button & WiFi lights go out and charging port light changes back from white to orange – will not finish powering up.
Press it again and same result.
Any clues greatly appreciated.