Since I nowhere found how to open it, heres how to do it:

First remove the label (use a hairdryer to heat it up)
or cut it, you can feel the hole
remove the screw under the label
Then remove the batterys and the two screws inside
put a srewdriver in the lower hole to press the undercover outside,
theres the first of 7 plastic snap-ins
then with a little help of a srewdriver you can remove it

Why do I do that?
There is nothing broken, but I´m trying to change the
two Buttons of channel and volume to one, like the 930
Maybe change the color of the front case
Has anybody an idea how to connect a c-mos battery?
Theres place enough and it would be fine not to lose
the settings after changing the batterys