@Taly
Thanks for reaching out to us.
Can you see the default extender Wi-Fi name which starts with TP-Link_extender XXXX after you reset ?
If you can't see default Wi-Fi name, that means you didn't successfully reset it. Please the steps below to reset and reconfigure.
1.Reset it to prepare the setup:
How to hard reset TP-Link wireless access points, extenders to factory defaults
Note: Most LEDs should flash once when you reset it.
2.Re-configure it via Tether app:
How to configure Range Extender via Tether APP
Reconfiure it via web UI:
How to configure my range extender via web GUI to extend an existing wireless network's coverage (new logo)?
More details please refer to our video if needed: https://youtu.be/oolmHBv7id8
If the above suggestions can't help you out, please share us with more details for the failure of the configuration, such as what's the prompt message when the configuration finished, the status of the LEDs in the device.