Sony Vaio Desktop PC wont start up?

I have an all in one Sony Vaio Desktop PC VGC-V3M.

It stopped working out of the blue the other day. I tried to switch it on and it just doesnt work. No power whatsoever. The PC has not been damaged or anything - thinking it was the power cable or socket, i changed these but with no luck.

Either the power button is gone or there is some sort of internal power failure? If is this then is it easy to fix or very expensive? I cant find any helpful information regarding this model anywhere.