My 4 year old Gateway laptop battery has finally died (I used to be able to charge it, but it wouldn't hold the charge, and would die before it even got past bootup). Now, I can't get the AC cable to charge the computer at all. Is there a simple fix here (a new AC cable?), or is it probably something bigger? I'm not using the computer; in fact, I sold it last night, but was told that it won't charge at all now.