At the edge of the control, you can insert (very carefully), the edge of a small screwdriver or a knife, (penknife type), and separate the two caps of the key holder.
Excuse me but the control of the keys does not have any screws to open the control and replace the batteries
Too easy. You must have a small screw near the key. You take it off and carefully try to open the control. The battery is a cr2016
Thanks! Your answer is awaiting moderation.