It was my daughters laptop and it suddenly stopped working and wouldn't power up. I have purchased and tried a new power adaptor and a new battery, but to no avail. Originally when the power adaptor was plugged in, the green light on the power adaptor went out and when I unplugged the lead from laptop it came back on again. Now the green light on the power adaptor stays on (as it should)and I have got a green light on the laptop (I think it means power cable connected) but when I push the 'power on' button, the green light on the laptop goes off and after a couple of seconds it comes back on again, but still not a sign of the laptop powering up. Can anybody throw any light on this.

Try removing the battery and booting with just A/C power.

I had tried it previously but I tried it again and still nothing. When I remove the battery and just connect the AC supply, there is no green light on the laptop, but when I plug the battery back in with AC supply it lights up. I have 2 batteries and one was flashing orange earlier but having left it on for a while it is now a constant green. I would suspect from that, that there is power getting to the battery and it is charging the battery, but for some unknown reason, its not powering the laptop up. I did suspect it could be the AC socket where the lead plugs in, but now I am thinking that the socket must be ok.

Hmm, was there a power surge? why did you change the Power Adapter? (I mean why do you think it went bad)

The Laptop seems to be doing a self test and failing it. I have seen this issue once, but I can't be sure if that is the case.