@lindaw1949 - There are a couple of battery options depending on your model. Check the Parts link at the top of the tutorial or just do a search for ‘sonicare’ on ifixit. You can also check the brand A store.

@Danielle10452 - The case is elliptical. With your tumb and forefinger, firmly squeeze the front and back of the case at the bottom as if you’re trying to make it circular. Simultaneously apply pressure to the tip (step 3).