Have only had my QC35 II's for about a week and today they were producing this awful, loud screeching feedback when I turned them on before putting them over my ears (battery was around 40%). This only happened some of the time, and I know that the feedback was easily eliminated when I put my head between the speakers, but still- I feel like this shouldn't happen at all... Why are my brand-new headphones screeching like that??
Welcome to the community, thanks for reaching out. I am sorry that you're having this feedback with your new QuietComfort 35 II headphones.
Do the headphone cushions appear to be securely attached?
If so, I would firstly suggest performing a reset of your headphones. Instruction on how to do this can be found below.
Turn off the headset and wait 30 seconds
Plug the headset into a wall outlet using a USB charger, then wait 5 seconds
Unplug the USB cord from the headset and wait 1 minute
Turn on the headset
Following this, check for any available firmware updates for your headphones. This can be done via a computer using a USB and visiting our firmware update website btu.bose.com, which will provide you with full instructions.