Is there a way to get my pwerbook to operate on battery pwr again? Operates fine on adapter, but not at all one battery power. One battery indicates charged up okay, but when I pull the adapter cord out the screen goes dark. Neither of the two batteries will make it run, in either battery slot, either separately or together. Sound like a hardware problem? Could attempting to run it with one bad battery (one may be bad) have messed up some logic so that now even the good battery won't get recognized?