Please do try these troubleshooting steps that may help in solving the issue.
- Start with a hard reboot, remove the battery and unplug its AC adapter then press and hold the power button for 20 seconds then try booting it up again.
- If it doesn't work remove the battery then try booting it up with just its AC adapter and see if it will boot up.
- Next to try is to reseat the RAM's, remove them all for couple of seconds then put them back in making sure everything is seated properly.
- If this will not work test the AC adapter if its supplying enough voltage or try a different AC adapter that has the same voltage.
- If all these will not work the problem lies on the motherboard.