I am having a issue with my Laptop. Asus as well. But yours may sound to be a battery only issue. It works when plugged in? And doesnt when on battery only? Pretty well sounds like to me its a answer in its own question. The battery sounds dead mate. Or could be the adapter. But if the adapter works while plugged in, then. Battery. Try another battery? And get a volt meter to check the connections to the battery to test if there is a charge or something there.