Hi Paul....
Below is a YouTube link that walks you through the process needed to open up the remote. The video was originally created to demonstrate how to reseat a loose transceiver circuit board; which requires opening the remote.
But be forewarned....opening up the remote is a real PILL! So, I highly recommend you watch the video a time or two to understand the process before you attempt anything and take your time.
I also want to let you know there's a lot of electronics packed into the remote. So proceed carefully.
Good Luck!