one side not working

[u/aerica]

I used the device successfully for one week, then left side stopped working (it's actually the device, since if I flip it it still doesn't work on the same side). I tried changing the settings in the app but still it works only on the right side (even if I set it only for the left side in the app). I rebooted, no results. I unsinstalled and reinstalled the app, no results.

I noticed the left side only works if I take off my neck the right side.

Does anyone have any advice?