Actually it comes off really easily. I sent an email to the service center last night and they responded within the hour to tell me someone would get in touch soon to solve the problem. They did and the cover comes off with a little suction cup that was supplied with the remote. It just takes a second and it pops right off. Then you just change batteries reassemble and that's it. It takes about a minute. Great system.
I went up in the attic to retrieve the box and inside was the suction cup and instructions on how to change the battery. I never cease to amaze myself.....LOL