Mine stopped working so I looked for a replacment. After finding nothing good to replace the RC-855, I disassembled and repaired mine.
Remove the screw inside the battery compartment first!
The bottom is a pan and the top clips into it in three places along the sides. Use a small screw driver or thin sturdy tool to pry the pan away from the top half in the groove along the side.
Another screw inside holds the PC board to the top half of the remote. All the buttons are connected together so no risk of getting them mixed up.
I cleaned the black conductive rubber pads and the PC board with alcohol.
It works great now, as good as new.
ho