HI,I see what your pb is. In fact, the back part (downwards while your using the 200) is held by two stategic points.
So:
1-> put off the four screws (that's OK, I read).
2-> now, put your 200 in the normal position (the back part downwards)and turn it so to view the battery container. You must have took off the two batteries AND the backup one (this is compulsory).
Take a screwdriver and try to use it to open the 200 from the side above the battery from the right.
You must be very careful.
If you have a problem, just stop and ask me because you may have other problems....
