Lithium Ion batteries which have been used for long periods in laptops plugged into the mains, and hence which haven't been charged cycled in a while, can appear to have died even when they're still good.
The 'fuel gauge' electronics in the battery can get out of synch with the actual battery state to such an extent that within minutes of pulling the mains lead you have a battery low warning. This tends to be followed by the machine doing whatever it's set up to do (hibernate or shut down) on the shortly following critical battery alarm.
By removing all actions on low and critical battery alarms in the power properties panel, you can allow the laptop to run the battery to a genuine state of discharge. Then recharge, at which point chemical and electronically indicated states often fall more or less back into line.
It's well worth a try before you write off an apparently dead battery. Sometimes more than one cycle is needed.