How to get the "Your battery is broken" message to go away?
Solution 1:
Maybe these instructions will help you to get rid of that message.
Added instructions from the link, Alt+F2, then type in gconf-editor.
Navigate to /apps/gnome-power-manager/notify/low_capacity and untick the value.
Or a single command:
gconftool --set /apps/gnome-power-manager/notify/low_capacity --type boolean false
Solution 2:
This worked for me:
If you have a machine with Windows as a dual-boot option, you can boot to Windows and let the battery recharge here. When the battery has recharged for a while, you can boot to Ubuntu and let it do the rest.