The battery cannot be charged while is displayed because the protection function is engaged. Charge the battery within the ambient temperature range of 5 °C to 35 °C (41 ºF to 95 ºF).

You need to turn the computer power on in order to charge your Walkman. Check whether the computer is in standby (sleep) or hibernation status.

Check that the USB connection to the computer is made properly.

There may be bad electrical contact in the connector. Disconnect your Walkman, and then reconnect it.

Use the supplied USB cable.

Your Walkman may not be able to connect properly to your computer when using a USB hub. Connect the Walkman directly to a USB connector on your computer.

Check whether the operating system and operating system version installed on the computer are compatible with your Walkman.

The battery may have deteriorated if you have not used your Walkman for more than a year. Contact your nearest Sony dealer.