Remove the batteries from the 'tivo' remote.
Now try the 360 remote again, and if all buttons don't work then insert new batteries and try again.
If that fails then you need to pair the 360 again by holding down the 'Live TV' (the one on the right hand side directly below the red power/standby button) and '0' button together for around 10/15 seconds. The Standby button should then start to flash followed by an onscreen message displaying 'Pairing successful - this remote will only work with this Virgin 360 box'.
You can also try the following:-
Put the 360 box into 'Pairing Mode' by pressing the Standby/On button on the front of the box for 10 seconds. Then using the remote control, press and hold the 'Live TV' button and the '0' button together for 10/15 seconds. And fingers crossed hopefully a message should appear on the screen confirming that pairing was successful.