M17X-R3 won't turn on

M17X-R3, Windows 7 Pro, i7, 16GB, 580M

A while ago I was suffering random shutdowns during gaming and came to the conclusion the GTX560M was failing, overheating etc. So I replaced this with a GTX580M which as long as I manually kept the GPU fan maxed out solved the issue.

Just now during gaming the laptop just differently turned off. Initially I couldn't reboot, so left it 5 minutes and then it rebooted into Windows. After about 10 minutes in windows (not gaming) the laptop turned off again. This time I can't get it to turn back on even after waiting some time, no post, no power light, no nothing.

I noticed that the blue light on the power adaptor cable where it plugs into the laptop wasn't illuminated. I unplugged the power adaptor from the laptop and the mains, plugged it back into the mains and the blue light tightened as expected, but as soon as I plugged it into the laptop the blue light turns off.

Any thoughts on the issue here?