Power light goes off when I press power button

Toshiba Satellite C55-A5310 Laptop, Windows 8. The power light comes on when I plug in the adapter but immediately I press the power button the light goes off. The light is amber when laptop battery is connected and white when laptop battery is removed.
It was working well and then I switched off normally and on switching on again .... bang this is where I am.

 

Pleas explain what

is?

To Start your laptop you would press the Power button.
To Shut down your laptop you should click on the Start icon > then click on the Shutdown text???

If you are starting and stopping with the Power button you will be doing "Hard" shutdowns???

 

I did the "soft" shut down.

 

Have you checked your Power Settings?

 

No. I do not reach that stage. The laptop does not power on.

 

It sounds very much like there is a fault in the Power on Button.
I don't think the RTC battery (CMOS) if flat/dead would cause a non-start.
The laptop should run on adapter power if the laptop battery is removed.
You would need to confirm that the adapter is 100% OK.