At first sight I was confused when I read the description at this step, 'cause it seemed that disconnecting the battery connector was optional, in order to eliminate static discharge. While it's a helpful advice in other circumstances (as mentioned as an example changing hard drives), when changing the battery it is not an option - you have to disconnect the battery connector.

It would have been better to mention the optional disconnecting recommendation in a side-note.

Other than that, an excellent guide!