Hello @sawsharp 

If all the Leds keeps flashing on a range extender,

• You could factory reset extender and see if RE still broadcasts Range Extender SSID

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

• Try a different power outlet for RE

If still the same, that unit could be defective. You could contact retailer or local support with product receipt, SN number and,  case details to check warranty. 

Hope this helps.