Search you tube for your model number, brand name, and the words "taking apart" or "repair". Chances are somebody has made a guide for how to disassemble it. The problem is probably due to the switch malfunctioning or being damaged. Even if it was easy to take apart, you probably still have to repair the switch.
I have Logitech g602 and I like it, but I hope I never have to take the thing apart.