USB device has exceeded power limits of its hub AND no sound

Yesterday no sound, but worse...Trying to connect to computer to charge gives me the message "A USB device has exceeded the power limits of its hub power. Clicking on the balloon states "A USB device has malfunctioned & exceeded the power limits of its hub port. You should disconnect the device." Plugging into the wall charger states "This accessory is not made to work with iPhone...want to change to Airplane mode..." Is my iPhone dead? Ideas please. Thanks