The partial detachment on the back of the device may result from moisture ingress, leading to rapid corrosion of its metal components.
As for the cause of moisture entry, a detailed inspection of each device's condition is necessary.
However, there are primarily two scenarios considered: External Impact.
If the device is exposed to strong external impacts or prolonged high-temperature environments, it may damage parts of the waterproof structure.
This damage can lead to internal water penetration when the device encounters moisture during daily use.
Battery leakage within the device, rather than external water exposure, has been recognized as a potential factor throughout the development process.