How do I open the battery compartment on my GS24?

Opening the battery compartment is simple. Locate the small, rectangular cover on the side or back of the device (often near the eyepiece). You will see a slight groove or indentation. Firmly press down on the cover with your thumb and slide it away from the body of the rangefinder. It should slide open smoothly, revealing the battery slot.
https://gogogosport.com/products/gs24bc