Here are some troubleshooting steps that may help in solving the issue.
- Start by doing a hard reboot, remove the battery and unplug the AC adapter then press and hold the power button for 20 seconds then try booting it up again.
- If it doesn't work try booting up your laptop without its battery and see if it will boot up or not.
- Next is to reseat the RAM's, remove all the RAM's for couple of seconds then put them back in making sure everything is seated properly.
- If it doesn't work do try a different AC adapter as well and see if it will boot up or not.
- Lastly, connect an external monitor and see if you'll get a display from it because if you do that means the problem is the built in display.
- If all these will not work the problem is the motherboard.