Please do try these troubleshooting steps that may help in solving the issue.
- Start by doing a hard reboot, remove the battery and AC adapter then press and hold the power button for 20 seconds then see if it would boot up.
- Next is to try connect an external monitor and see if you'll get a display from it because if you do that means it's the LCD display that has the issue, you'll need to check the ribbon cable that connects the LCD to the motherboard.
- If these doesn't work do check the AC adapter if it's supplying enough voltage or try a different AC adapter.
- Do also reseat the RAM's, remove them all for couple of seconds then put them back in making sure everything was seated properly.
- If all these will not work the problem lies int the motherboard itself.