You may be using an AC adapter with an unsupported voltage and current.
The voltage and current of the AC adapter supported by Pocketalk are as follows
Charging voltage (input): up to 5V
Charging current (input): 0.5A to 2.0A
Charging terminal: USB Type-C
AC adapters with voltages and currents exceeding the above cannot be charged properly.
When using a quick charger, it is possible that the voltage and current may exceed the above limits, so please use an AC adapter with a voltage and current within the above limits.
And you can also try to charge the battery by inserting the supplied USB cable into a PC or other device with a USB port.
The voltage and current of the adapter may be indicated on the adapter itself.
If there is no description, please ask for the manufacturer.