Perform the following steps:
-Remove the battery and Power adapter
-Press and hold the power button for 30-45 seconds (with battery and power still removed)
-Insert just the battery and attempt to boot the laptop.
-Insert just the power adapter and attempt to boot the laptop.
Is the laptop is under warranty?
Remove the hard drive and attempt to boot the laptop. Do you receive any display or error?
Remove and reseat the Memory modules. Attempt to boot with one module at a time.
If still having issues take a look at the steps below.
Black Screen Issues and Troubleshooting