Toyota Yaris 2011 tomtom 13836 head unit, cant switch to aux

[newkid123]

Hi, 

i recently bought a toyota yaris from 2011, with a tomtom 13836 (TNS410) head unit in it, however i want to use bluetooth connection to play music and want to use a aux cable to do so however i cannot switch to the aux input on the head unit. i have tried following the direction from the user maual and instead of getting a screen to enable the aux function on the tom tom display i just get a blank screen with 2 sliders on it for brightness and contrast. i have updated the tomtom but cannot think of any thing else that i can do to get it to work any help would be appreciated.

Thanks