Does anyone recommend disassembly of this device or can I send it back to Sony?

I found them to be quite easy to take apart with a bit of filling with a credit card similar to the newer xm4 disassembly guide. Sony WH-1000XM4 Battery Replacement - iFixit Repair Guide I unscrewed the outer cover to inspect the main board and found no visual damage. However upon adjusting the cable inside the ear cup and removing the protective tape in the central terminal I was magically able to get the left hand side working. So if anyone else has this issue I recommend disassembly to have a fiddle around with the internal speaker cable. Update: Still no permanent fix 2 years later. Today I tried all of the cabeling and even removing some of the insulation to try inspect where it could have issues. In the end I just accidentally tapped the left speaker driver, Which is a big magnet (oops), and it seemed to resolve the issue. At least for now. These headphones still sound great and really hold up well.

Thanks for this guide. I was able to repair a loose cable on my XM3s with this disassembly information.

Since the design of the models are mostly the same it would be nice to have a similar disassembly guide on the XM3 website too.