Replacing a worn Joy-Con battery extends its life—here’s how to do it safely. Buy a Joy-Con battery replacement kit (includes tri-wing screwdriver, Phillips screwdriver, new battery, and pry tools) from Amazon or electronics stores. Power off the Switch and remove the Joy-Con. Use the tri-wing screwdriver to remove the four screws on the back of the Joy-Con. Pry open the case with the plastic tool—start at the bottom near the strap connector. Disconnect the old battery’s cable from the circuit board (use the pry tool to lift the connector gently). Connect the new battery’s cable, ensuring it’s seated properly. Place the new battery in the compartment and snap the case shut. Screw the back panel back on and charge the Joy-Con for 2 hours. Note: DIY replacement voids Nintendo’s warranty—if under coverage, use official repair first. Test the battery life by playing a game for an hour—should last 20+ hours with normal use.