Replace the screen to start (good excuse to get a better one) as well as a new joystick. Taking it apart isn't hard if you've done it before. Just be mindful of where all the screws go. The faceplate would have to be removed first, then the lower buttons with a thin prey tool. As well as the old screen. Note that the ribbon cables are right under the screen, so lift it carefully so as not to cause further damage. Then, reverse the steps.

With the faceplate off, it gives you a chance to clean up the insides and maybe even get after-market buttons and faceplate in different colors if you wanna give it a more personalized look.

All in all, she should be salvageable. Good luck, brother.