I suspected the battery in my Bose QuietComfort 35 headphones was on its way out. But it ended up being a different issue entirely, and fixing it cost a fraction of what Bose would have charged for a replacement -- with no special tools or skills required.
The C&K replacement switch (they're cheap, buy one or two spares): https://www.digikey.com/en/products/detail/c-k/JS207011SCQNR/6071286
My favorite spudgers: https://www.digikey.com/en/products/detail/menda-easybraid/35622/657780
Replacement QuietComfort ear pads (affiliate link): https://amzn.to/3Txqif5
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Music by Epidemic Sound (https://www.epidemicsound.com).
Intro music by BoxCat Games (https://freemusicarchive.org/music/BoxCat_Games).