Did you follow the instructions below:
Connect one end of your Ethernet cable into one of the yellow sockets on the router where it says LAN, then connect the other end into the socket on your YouView Box where it says ETHERNET (make sure your router is on)
Connect one end of your HDMI into your TV, then connect the other in labelled HDMI into your YouView boxUnplug your aerial from your TV and connect it to the ANTENNA IN socket on your YouView Box. Alternatively, you can use the white aerial cable that came with your YouView Box. If you are using the indoor aerial then just plug it into your YouView box.
Connect one end of the black power supply cable into your YouView Box as shown below
Connect the other end into a power socket near your YouView box
Switch the YouView Box on at the back then press the power button at the front (and switch on your TV), when you see the middle light on your box come on that mean your YouView is ready to use.You can also go to this pdf form: http://m1.ttxm.co.uk/sites/rightnow/TV/TVSIGUIDE1013V5.pdf and it will talk you through the whole thing.If you can't remember if you went step by step, please take everything off of your YouView box and start over.If you are using the remote to turn on your YouView box make sure you are using fresh batteries.