Sleep light comes on, no chime no boot.

Hi there.

My MacBook shut down recently doing an iTunes update and did restart but not boot.

I ran AHT and it said this disc cannot be used with this Mac but it is the correct disc that came with the machine.

I did a PMU reset , and it shut down on the second chime and would not boot. No chime no post. The sleep light comes on and stays on, until I power off.

I can hear optical disc activity and nothing happens.

I have tried removing the ram and reinstalling it. And this does not work.

Holding the power button for 20 seconds without battery and power does nothing.

Any ideas? Thanks so much.

Yes , in my case it was a failed GPU. Once reworked / replaced it came back to life.