|The lit green led is probably the one that indicates the AC adapter is plugged in.|
That's often on even when the computer is not running.
You can confirm that by unplugging the AC adapter from the laptop.
If the battery is installed when you plug that in, the led may go out in a short time if the batteryis fully charged, but it will always light up when you first plug the AC adapter in.
It's extremely unlikely there's anything wrong with the power switch, but if the power button is sticking in the down position such that the power switch is always on, the computer will NOT start up.
A hard drive problem does NOT cause the computer to not boot at all.
Video problems are common on laptops, however, if you hear no beep while booting and the grandson did hear that before, and if you see no other leds light up, the laptop has hardware problems.
Ask your grandson those questions.