Please do try these troubleshooting steps that may help in solving the issue.
- Do a hard reset, remove the battery and AC adapter then press and hold the power button for 20 seconds then see if it will boot up normally.
- Next is to test the AC adapter and see if it's supplying enough voltage to power the laptop or better yet try another AC adapter that has the same voltage.
- If there are lights on the laptop indicating it's on connect an external monitor again and see if you'll get a display.
- Also do try and reseat the RAM, remove them all for couple of seconds then put them back in making sure that they are all seated properly into each slot.
- If all these will not work the problem lies in the motherboard of your laptop.