Please try the following steps. The battery could be fully drained and may require specific procedures for it to be powered up.
1.Connect your Pocketalk device to the USB charger cable and begin charging the device.
2.Press and hold the Power Button at the top-right portion of the device for 60 seconds.
After 60 seconds, let go of the power button.
3.Leave the cable connected and let the device continue to charge for 10 minutes.
After 10 minutes, tap the Power Button to see if the "Charge icon" is displayed.
If the Charge icon is displayed, this indicates that the device is being charged properly.
Continue charging till the battery is fully charged.
You can also refer to the video below
Battery Doesn't Charge / Device Won't Turn On