Hello  @Jawahery 

If the power led keeps blinking on the range extender, you could try to factory reset the extender:

RESET: With the extender powered on, use a pin to press the RESET button until most Leds flash once.

After factory reset, please check if range extender broadcasts any Wi-Fi SSID like Range Extender, TP-link Extender etc., if not, it might be a faulty unit,  you could contact the local retailer or local support check device warranty for the certain unit. 

If range extender responds to a reset or still broadcast the Wi-Fi SSID,   you could install the range extender as instructions here 

Configuration Guide:TP-Link Range Extender Setup (Range Extender Mode)