My Lenovo T420s on Ubuntu 13.04 notebook suddenly stopped waking up from suspend. It used to wake up when opening the lid, but now the screen stays blank, the power button slowly flashes and doesn't respond to presses. There doesn't seem to be any activity - no HD or fan noises - it's as if the lid opening or power button pressing isn't detected.
What sort of information do you need to narrow down the problem?
(btw, if this can't be fixed easily, I wouldn't mind if closing the lid powered down the notebook completely, but power options doesn't seem to have this setting).