have you tried using something like a needle to pry it back out? if that doesnt work you will need to remove the screen to access the buttons. you should watch a few youtube videos first to see if its something you want to try
i use oca adhesive sheets for all screen replacements. you need to cut it into strips to size but so far its the best solution i have found as it never lifts afterwards. its a bit tricky to work with but its worth the trouble. it bonds the digitizer to the frame very well and is thin enough so as not to leave the screen standing proud of the frame. i have also used b700 glue for frames with very thin edges to bond too. the oca is hard to work with when it needs to be cut very thin.
hope the schematics helped. did you know that the power/camera board can be got on its own. they can be found on ebay and are straight forward to replace. would save a lot of messing about. just make sure its the right one as i think there are two types.