The SONY wfsp700n displays the causes and solutions of the failure
If it is idle for a long time, the internal protection current will also be exhausted, in this case, when you charge, the earphone can not be opened normally.
< br >
The original charging device charges the Bluetooth headset for about 20 minutes, and tries to open it, if it cannot be opened, the activation fails, because there is a protection and voltage problem with too much current inside the headset.
< br >
There is a battery inside the headset, it can be understood that the protection battery, there is voltage, it can work normally when charging, but the protection battery is out of power, direct charging, it involves whether to activate the battery inside, it may be damaged, but it is also possible to restore use.