Please do try these troubleshooting steps that may help.
- 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 the same problem will persist, do try powering the laptop without the battery and just the AC adapter connected.
- Do try a different AC adapter that has the same voltage if the laptop will still not boot up.
- Proceed with reseating the RAM's if it will still not work, remove all the RAM's off the laptop for a second then put them back in making sure everything is seated properly.
- If all these will not work do contact Lenovo for a repair if it's still under the factory warranty.