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what does the black screen say and do you have you operating system disk , what os mac is it
Let's start with something simple...hit your F2 function key 3 or 4 times and see if you get a screen
The issue you are having can be a few issues, from simple to not
so let's try this next....
Disconnect the power, and pull the battery then turn the MB on (to drain any lingering power). Then reconnect power and try again.
I feel you have a serious issue, you really do need that operating cd, I am going to opt out so that other MAC experts that may have more ideas can help you.