Here's the IFIXIT guide you'll need to follow for either: MacBook Pro 15' Retina Display Mid 2015 Upper Case Assembly Replacement. While more complex if you're not careful you can damage the battery in the process. Or, take apart the upper case so you can replace the keyboard subassembly. You have two ways to do this, either replace the complete upper case while expensive it is by far the least amount of work.
