you need to remove the memory module from the back of the computer and reseat it again then after that follow the steps below.
Unplug the ac adapter. Keep ac adapter unplugged.Remove the battery and keep the battery unplugged.Hold the power button down for 15-20 seconds. (Nothing will appear on the display and none of the lights will light up.)Release the power button and plug in the ac adapter ONLY. (Please note that a power indicator light should be lit on the ac adapter when it is plugged in).Normally power on the notebook.
Computer Hardware Engineer
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