Hi,
Please do try these troubleshooting steps that may help in identifying or solving the issue.
- Do a hard reset first, remove the battery and AC adapter then press and hold the power button for 20 seconds then see if it will boot up.
- If it will stay black with the indicator lights on connect an external monitor and see if you'll get any display from it. If it doesn't display anything it could be a bad motherboard already but if does show display that means it's the built in display that is faulty.
- Do try and reseat the ram as well, remove them all for couple of seconds, put them back in and see if the laptop will boot up.
- Lastly is to test the AC adapter if it's supplying enough voltage to power the laptop or better yet try another AC adapter that has the same voltage.