Hello @Brooksy16 

If you have factories reset, it will broadcast default SSID TPLINK _XXXX, please check if you can see it on different devices like mobile devices and  laptop. 

Check the Wi-Fi Led on AV600 extender, and Wi-Fi Led should be ON. 

You may download tpPLC Utility and change the Wireless settings for Powerline unit:

How to Change Wireless Settings using the tpPLC Utility (Blue UI via PC) 

Hey @Brooksy16 

Sorry for the late reply, is your phone connected the Wi-Fi of powerline extender, if so you could download tpPLC APP and change wireless settings.

How to Change Wireless Setting Using the tpPLC App (Smartphone)?

If still does not work, you will need to factory reset Wireless extender and repair 2 powerline units,

RESET  : with wireless powerline unit powered on, use a pin to press the reset hole on the bottom until most Leds flash once 

Wireless powerline unit should broadcast TPLINK XX default SSID after a successful factory reset, connect  to WiFi using the 8 digits wireless password on the label of unit. 

If wireless powerline unit does not respond to a factory reset, or does not broadcast SSID, it might be a defective unit.