Welcome to Android Central! After you remove the backing, make sure that all of the clasps are loosened and you will need a Philips head screw driver to remove the screws to loosen the battery connector. That should do it. If you could please sign up on our site, when your question is answered you will receive a notification and not have to search for it later. It would also give you the ability to help and share your own knowledge with other guest!
Re: I have a nexus 4 android version 5.1.1. Can I change a low battery?
Use a Torx T5 screwdriver to remove the backing. Use a thin piece of plastic (Such as a credit card) to pry up the backing. Next, use a Phillips #00 screwdriver to remove the battery. Hope this helped