Acer aspire 4520

It might be a problem with the on-board part of the power circuitry. If so, hopefully this is a discrete card, not built onto the motherboard.

what is a discrete card

Discrete=Separate(=Modular ?) The advantage being that a single small board could be replaced rather than the whole motherboard.

I trust that the work you've already had done was under warranty and -- even if out of warranty -- you are entitled to look to the retailer for help.

that is the same problem with my laptop same model of acer. please somebody out there tell me where can i buy that power circuit, i am here in jubail, and i gone to different shops here in jubail center but i can not find