Remove the screw, then get an old credit card (or bond card, etc) that you don't mind trashing, and slide it into the edge wherever you can get it in, once it's in slide it along the edge whichwill pop open the clips.
What is it that has stopped working, does the LED still light up when buttons are pressed but no IR signal is being sent, if so, try replacing the IR-LED. If the remote does absolutely nothing, check the battery connections.
Rob
http://www.hifi-remote.com