Nothing comes up on the screen at all? You said "it flashed" what flashed? The screen or some status light? Do any lights come on or the fans start? Try it with an external screen, plug the screen in, turn on the laptop and close the lid right away, it should detect the monitor as the main screen and give you a display if the issue is the screen. If the motherboard has a removable CMOS battery you can try removing that along with the main battery and then hold in the power button for 30 seconds. Plug in wall power only and try to turn it on. If it comes on and stays on for a bit, plug in the batteries and see if that works.