Hi,
Please do try these troubleshooting steps that may help in solving the issue.
- Start with a hard reboot, remove the battery and AC adapter off the laptop then press and hold the power button for 20 seconds then try booting up again.
- If these doesn't work do test the AC adapter or try another AC adapter that has the same voltage and see if it will boot it.
- Next is to try to boot the laptop without its battery and just its AC adapter.
- Another troubleshooting step would be to reseat the RAM's, remove them all for couple of seconds then put them back in making sure everything is seated properly.
- If all these will not work the problem would be the motherboard.