Upon getting a Tello, the firmware is most likely so outdated that nothing will work, including the option from the Tello application to update the firmware. In order to update the Tello forcibly, perform the following steps:
remove the battery and USB cable from the Tello,
hold down the button the side of the Tello,
plug-in the USB cable,
slide in a battery,
when the green LED goes off, release the button on the Tello,
open the Tello application and update the firmware