Fighting Fires is the Same in 99.9% of Cases
Think my friends, please think! Virtually all fires require THREE components: Heat, Fuel and Oxygen(*). Remove one and fire goes out. The use if water to fight battery fires is no more than an attempt to cool, removing the heat. At least in theory, the most effective way to cool an existing fire is by using a strong source of CO2. Those on-board battery containment vessels, once sealed, prevent new Oxygen from reaching the battery. Adding water to the container helps, but is not essential.
(*) in absolute fairness to the few chemists and 'experts' out there, yes, there are a few substances that can create their own Oxygen when burning. Pure Sodium and Magnesium come to mind and I'm sure their are a few more. They are NOT the issue here! In practical terms, for use by cabin crew, their training instructs them to isolate the offending device in one of those sealable containers and to add some water, IF INSTANTLY AVAILABLE and seal the container.
CO2 remains extremely effective, for both cooling and Oxygen displacement, but is rarely available on aircraft. Why? The extinguishers are heavy steel 'bottles,' and weight is always an issue. In addition, other Oxygen displacement agents are available - and routinely available on aircraft. Several of the Halon (sp?) formulations come to mind. While also compressed gasses, their containers may be far less robust, their weight significantly less.
Lastly, SOME types of Lithium batteries truly are subject to nearly spontaneous combustion. That's why SOME types of Lithium-containing batteries are subject to extremely tight air freight rules. That said, Not ALL types of Lithium containing batteries run that risk. Many formulations are every bit as safe as are the ordinary 'alkaline' or even the older, Zinc-Carbon batteries. For the very best protection against unwanted fires in difficult places, know your critter and/or consult a professional. IMO, every user of a consumer level 'Lithium' battery operated device should know the specific type used, perhaps marking it on the back of the device's case. Some types of 'Lithium,' batteries are rechargeable, while others are not. Be safe, if course, but there is no need to panic concerning consumer level devices.