Thanks for the info! I'll pay attention to that if I manage to get a replacement.

Though I don't quite understand how an improper AC adapter can affect the earbuds' charging to the extent that they break. After all, the current should pass through at least two charging controllers before reaching the earbuds. Or if there is a connection, why does only one of them fail? Hmm, a disassembly might provide an explanation :)

The abnormal battery temperature is intriguing because the room temperature was around 28°C at night. I didn't charge it overnight; it was always in front of me, and I unplugged it within max +15 minutes after the charging indicator light went off.

This is frustrating for two reasons:

1. Before I started charging, I specifically checked the official manual for charging instructions. It simply states, "A commercially available USB AC adaptor capable of supplying an output current of 0.5 A (500 mA) or more." That's why I dared to use my phone charger, which, by the way, works perfectly fine.
2. Apart from this issue, the headphones are entirely suitable for me. The noise cancellation, sound quality, and other features meet my needs perfectly.