Here is a useful Apple document giving steps to follow when your Mac
does
not boot:
http://docs.info.apple.com/article.html?artnum=106464
For laptops that have problems relating to switching on, waking from
sleep,
and not charging, reset the Power Management Unit (PMU). The PMU
controls
waking and sleeping, hard disc spin, backlighting, charging, and such
like.
It is an integrated circuit that runs a control program (micro-code)
that
can crash. It sometimes needs to be rebooted itself.
Look here for Apple's documentation on resetting the PMU:
http://docs.info.apple.com/article.html?artnum=14449
