New 360 Box not starting up correctly

Had a new 360 box supplied last month but have several recurring issues around powering it up : 

1 / If it actually starts up, it sticks on one channel and won't allow you to change it. No volume and the box does not respond to any of the commands from the remote control nor the buttons on the box (power / plus / minus).

2/ The only way to resolve the above is to unplug everything and start again, via a combination of soft reboots on the 360 Box.  Takes about 20 minutes before it finally powers up properly

Once it's active it's mostly fine (although some advertised functions on the remote are not supported, like back to previous channel for example). 

I've followed the installation / trouble shooting tips but the above keeps happening.

Is this a fault with the box or is there something in the settings I've missed? (I've tried changing the power settings but this has no impact)

Broadband WiFi works fine without any issues.