Rollover upgrade

I have just bought a tt xl black with firmware 8.083. When I set the clock it shows the time briefly then reverts to zero. It navigates ok but shows no time. I connected to tt home for the rollover upgrade but get the message “device is up to date”. I have removed everything and re installed it but no change. I upgraded a tt xl for a friend and all went fine and having checked it has firmware 9.541 and as I said seems to be fine showing correct time. Can anyone help please?