iDrive Screen not turning on

[col320ce]

I just bought the car, and the screen was flickering, but eventually stayed on, and the seller said this had been going on for a while. Now it's not turning on at all; however, in the dark, I can see that the backlight is on. I haven't disconnected the battery to try to reset it, as I'm not sure if this will cause other problems. I have not worked out how to reset it by pressing buttons (the CD eject and MODE buttons pressed together do nothing). I'm assuming it is not a fuse as the back light is on (but this may be a bad assumption).
I'm guessing it is a bad connection, given the glitching before it went out, and I think there is a cable connecting the radio to the screen that might be at fault.
Any suggestions
Thanks!
Col
2012 128i convertable