Use this guide for disassembly and for resolving jammed or finicky shoulder buttons.
Take the battery cover off by releasing the locking tab and hinging the cover away.
Remove the six back panel screws using a Tri-wing Screwdriver.
Remove bottom back panel screw with a Phillips #1 screw driver.
Remove the back panel by pulling away with one hand and the front secured in the other hand.
Remove left and right triggers by lifting and pulling them away from the system.
Do the same for side panels