The top switch slider is broken, it feels like it does not engage, to fix the thing the remote must be opened. The front of the remote says RC32, there are 6 screws that need to be removed to take it apart. Two screws are located in the battery compartment, they can be accessed by removing the slide-on battery cover piece. Additional screws are located behind the dark gray oval panel on the front of the remote.
regarding basic designs. More detailed information is found in textbooks, they're boring but effective.) The size and shape of each snap fit can be altered to control how difficult removal will be. The three here require only a small amount of pressure (upward).