Here are some 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.
- Here's a video guide on how to disassemble the laptop: https/www.youtube.com/watch?v=hsQFt9c6E0Q
- If it will still not boot up, leave the battery out off the laptop then connect the AC adapter then see if it will power up.
- Do also try a different AC adapter that has the same voltage and see if that will work or not.
- If using a different AC adapter will still not work proceed with reseating 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 lies in the motherboard.
- Do contact ASUS for a repair if it's still under the factory warranty.