Hello,I have dug my Dell inspiron 4000 out of the back room to re-use it. The battery was no good and so I replaced it with a new one. However it does not power up without the a/c adaptor connected. The battery shows full charge ( pressing the F2 on boot-up ). I cannot seem to get the blue function key option for the battery to work either. Am I doing something stupid or is there a set-up I need to do. The manual that came with it is a waste of time. Regards Pete