I am the recipient of a Dell Inspiron 6400 which I received with a dead battery although the ac adaptor would power the unit. I obtained a new battery for it and installed it thinking my problems would be over, but sadly I'm getting the AC-Adaptor = Unknown Device Installed with BIOS version A14. I've reviewed this. But my question is does anyone know of a version of the BIOS that will ignore the blocking circuit and allow the battery to charge? I don't really want to throw more money at this old laptop buying an AC adaptor when the problem may be at board level. but I hate to pitch it because otherwise it works fine.