There are many instances of the laptop does not boot:
1) Try to removed the battery and plug via AC if that will work because chances it might be already dead. (mostly that may not work)
2) Check any wirings from the laptop especially the Hard Drive or RAM which may causes not to boot correctly.
3) Does the monitor of your laptop is working? Because its has a tear level that might damage the signal connection therefore you heard the fans working but everything is totally black.
4) Beep codes may equivalent to the failure of hardware: http://www.pcmag.com/encyclopedia/term/38515/beep-codes
