Can’t connect/sync a controller to my Xbox, or find any WiFi’s

I brought an Xbox off some guy a while back and it worked fine for a while, connected to everything, all of a sudden it wouldn’t find any WiFi when I searched, tried hard reset etc, looked online found nothing, then my controller sync button went too, no flashing on the Xbox when holding or pressing it, the controller just continues to flash and connects to nothing, I’ve been using a wired connection on both WiFi and controller for some time now, and today while gaming my controller disconnected and never connected again, tried 3 different controllers with 3 different wires and none of them connect atall, just connect to the other Xbox, tried all I could find online again, nothing. Any help please? Much appreciated