If ya hold down the unlock button on the keyfob, the rear window drops - it is a feature to allow shoppers to put there wares in without opening the rear door. Raise it by putting the key in the taigate lock and turning to the right - hold there until the window is all the way up.
I found this problem occured several times when I slipped the key fob in my jeans pocket - the button got pressed as I walked away.
Learnt to be careful about that.
You may need to recalibrate the rear window by running it down and back up again.
The horn beep means it believes a door, the bonnet or the rear window are not fully closed.
