Apple TV networking failure

I've got a 4th generation Apple TV that up until a couple of days ago was connecting to ethernet and wireless networks without a problem. It's running the latest software. Now when I remove the ethernet cable it does not switch to trying to access wireless networks. When the ethernet cable is plugged in it does not retrieve an IP address but behaves as if no cable is plugged in. I've reset the software but now can't get past the initial stage as it will not connect to any network. It's just over 12 months old so I guess it's out of warranty.

Anyone got a tip for me?