If we're talking about lithium battery incidents in the passenger cabin, then most have been caused by passengers not protecting the battery terminals from short-circuit. The challenge here is educating passengers as to how they should protect spare batteries.
As for guidance on actions for cabin crew, the ICAO "red book" provides very clear guidance for cabin on how to respond to a fire involving lithium batteries.
1. deal with the fire using halon or other available fire extinguishers; and
2. cool the device/batteries by dousing with water or other non-flammable liquid.
This has been demonstated as putting out the fire and preventing subsequent reignition from the overheated lithium battery.