Yes, there is a specific procedure of button pressing/pedal pushing to get the rear electric parking brake to disengage into "maintenance mode." Otherwise, you won't be able to change the rear brakes. Can be found with a quick search, but takes a few tries to get right. You'll hear the electric motor when it works.
You'll also need a pretty complete tool set as the front and back brakes use different hardware (from what I recall, backs require a very large Torx bit which I didn't have and fronts required a very large hex bit I didn't have). A piston retracting press also helps a lot.
All in all, not a bad job as long as you have the right tools and get the EPB procedure right.