How you can fix dead DJI Spark batteries using a 9V battery, a CP2112 board, and DJI Battery Killer (should work for other batteries too) : r/drones
The Ultimate DJI Spark Battery Guide - YouTube
ULTIMAXX DJI Spark Car Charger with USB Connector for DJI Spark Batteries - Walmart.com
DJI Spark Intelligent Flight Battery - DJI
Amazon.com: Multiple Battery Charger with 4 Channel Rapid Balance Charger Ports and 2 USB Ports for DJI Spark Drone Battery and Remote Controller 6 in 1 : Toys & Games
Dji Spark Battery - Original New Spark Battery for Spark drone intelli – RCDrone