Try below:-
*Unplug the AC cord
*Remove the battery
*Locate the memory cover on the underside of the notebook
*Unscrew the one or two screws securing the memory cover, and lift up to remove the cover
*Gently slide (away from one another) the metal retaining clips that hold down the module.
*The module should pop up
*Remove the module
*Reinstall the module (removing and reinstalling the module is apparently enough to rectify the contacts)
*Replace the module cover and the battery
*Attach the power cord
*Try to power up
Hopefully, this works for you!!!!!!!!!