Log in to the Home page (Refer to "How can I access the Home page?" in the Basic Settings module). Go to Settings -> Wi-Fi -> Basic. Click the 
icon next to WiFi Password to check the password.
Method 2:
Reset the device to factory default settings.
Use a paper clip or a blunt pin to gently press the reset button for 8 seconds.
The Wi-Fi key will be reset to the default password, which can be found on the bottom label of the device.
