Lock button is broken, battery is wonky?

My iphone's lock button broke a long time ago and I never got it fixed as I started to use assistive touch, A couple months ago i dropped my phone and whenever people rang me It would go straight onto speaker and noone could hear me, eventually it went back to normal but It fell out of my pocket the other day and it completely wont come on, i can see the screen trying to light up and i managed to touch the screen and music started to play just i cant see anything. I got my sister to take off the back and the battery looks out of place, Is there anyway of fixing the phone or now the batterys out of place is it completely broken? I have ordered a new battery and lock button as my sister is very clever at fixing phones computers etc but im worried its been a waste of money if its going to be impossible to fix? thanks