No Display or Disk activity.

Tried removing battery and booting with charger plugged in? If still no response from the computer, take a multimeter and check the output voltages on the charger; you can also use a multimeter to check for correct battery voltages. If things seem normal with both battery and charger, then it is time to start inspecting the laptop itself which probably will require that the unit be opened for visual malfunctioning component inspection and the taking of various multimeter measurements such as voltage, continuity etc. Also try searching using Google, Google Images, Youtube etc for known issues with your unit.