Hi,
Please do try these troubleshooting steps that may help but if not I would say it's a motherboard problem.
- 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 back up.
- If it doesn't work try to reseat the RAM, remove them all for couple of seconds then put them back in making sure everything is seated properly then try booting it back up.
- Next to try to remove its battery and boot it up with just it's AC adapter.
- Also try removing the keyboard from your laptop, unplug the ribbon cable that connects the keyboard to the motherboard then connect an external USB keyboard and see if it will work because if it does that means the built in keyboard is the problem.