As always, IFIXIT provides exactly what you need to be successful.
My phone was dying most days around 3 pm unless I charged it. It also died regularly with 20% battery life remaining.
Even though the level of difficulty says moderate I would rate this as easy. You have to remove three sets of screws and a few connections to the screen. Im so happy that IFIXIT provides these how to manuals! The world needs more manuals like this for a wider variety of items like cars, bikes, lawn mowers etc. DIY revolution!
Take your time and dont force anything.