If your Joy-Con’s shoulder button (L/R, ZL/ZR) isn’t working, start by cleaning it. Use compressed air to blow dust out from around the button—hold the can 6 inches away and spray short bursts to dislodge debris. For sticky buttons, dampen a cotton swab with isopropyl alcohol (70%) and gently wipe the缝隙 between the button and the Joy-Con case, avoiding liquid inside. Let the Joy-Con dry for 10 minutes, then test the button. If cleaning doesn’t work, reset the Joy-Con by pressing the SYNC button for 5 seconds, then reattach it to the console. Update the Joy-Con firmware: go to 'System Settings' > 'Controllers and Sensors' > 'Update Controllers'. If the button still fails, the internal spring or switch may be faulty—contact Nintendo Support for repair, as this is often covered under the Joy-Con warranty. Avoid pressing the button too hard, as this can damage the internal components over time.