If you still have the button,and its not broke,it's a somewhat complicated fix. Camera has to be taken apart. Mainboard on rear panel,along with battery compartment,and all flex ribbon boards have to be removed to get at switch. Do not bend or crack flex ribbon boards,they can be expensive. Now once you get to switch,simply put pressure on green lever from inside and push black knob on from outside. It is imperative that you make sure all ribbons and connections are tight,before reassembling camera. As you can see,this is not easy. Leave it to a professional. if you decide to sell it email me.