you've come across the annoying T8 screws with a pin in them.
That makes them a T8H screw.
Here is the tutorial about dealing with them.
Step 1: Pin Pin Pin!
Check out those pesky T8H screws!
The easiest thing would be getting a T8H screwdriver, but they are hard to come by.
Here's the next best thing and it's pretty simple.
Things you'll need:
Small Flat Head Eyeglass screwdriver,
also known as watch screwdrivers or watchmaker screwdrivers(dollar store)
T8 Screwdriver (auto store, computer parts store, or radioshack) -
(I personally think the T9 fits better, but w/e is easier to find will work)
xbox 360 controller that you want to open
Step 2: Screwdriver + Drill
Take your mini flathead screwdriver and stick it in the drill.
Usually you can just put it in, and the end handle spindle won't stop the clamps from tightening it.
If it does stop the interior drill clamps, cut it off.
Step 3: Twist and shout!
It should wedge perfectly between the pin and one of the screw walls.
Slowly start turning the screwdriver clockwise with the drill, yes, You will be tightening it.
Step 4: Snap!
Now grab your trusty T8 Screwdriver and open your controller!
Step 5: Other Solutions:
If you don't want to buy a T8 screwdriver,
Put the screwdriver in the drill,
Wedge the screwdriver into the screw,
and put the drill if reverse VERY SLOWLY!
It might be able to unscrew the screw.
Buy a T8H screwdriver. They are around $5.
Use a screwdriver and hammer.
Stick the screwdriver in the wedge and hit it.
Hopefully it'll pop the pin, but you might damage the screw.
Buy a pre-modded controller.
Ebay search "xbox rapid"