I was messing around last night trying to pull up the hidden display but i ended up getting the Test screen.

I think i am the first to discover this?

Before you start the car hold down the AM button,H clock button and the 00 clock button.

Now put the key in and turn but not totally on just to view the radio.
Still holding the Test will display. You can use the H buttone to scroll up. I noticed that going through it on of the features was all the display was lit. So now it just trying to unlock the rest.

Hope this helps.

Thanks