Interruttore di alimentazione 3 posizioni di ricambio per Bose Quiet Comfort 35 QC 35 & 45 OE

(This could fix the issue with your headphones not turning on. However, the issue could be with the plastic button that connects to this switch and not the actual switch that's the problem. I'm not responsible for any issues you have if you have a problem doing it, just passing along the suggestion.).

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