The laptop should run without any batteries installed. Bad batteries should be replaced. If you have no intention of doing so, remove the bad battery and run on AC power. The issue with the power button could be unrelated. The button may need replacing, repair or servicing. Replacing the bad battery should get rid of the error, but it won't fix unrelated issues (power button). Something on the power circuit could be going bad, but you wouldn't know until the board is checked by a qualified technician. Replacing the battery is a first step and one that you can readily do unless money is the biggest obstacle (understandable). At least get the button checked.