Usually once you smell the burning, it's too late. If indeed it is a motherboard part, you also need the right equipment and skill to replace the bad part, if you can find a suitable replacement (not an easy task.) You could take it in for repairs, but it might cost you more than a newer replacement laptop, depending on exactly what it is... plus most places charge for a diagnostic session (some will refund it if you go with them for the repairs though.)
Best bet is as Saga Lout stated: retrieve the hard drive to save and recover any data on it you wish to keep, especially if it's financial or personally identifiable. The RAM, maybe salvageable for resale, or might not be. The same with the screen or any other parts, so Recycle or, if you're careful and know what you're doing, you might be able to part it out.