How to open it (don’t pry).
The entire rear cover slides down.
Do this exactly:
Flip it over (buttons facing down)
Note the ARROW at the top of the remote.
Grip the rear cover top half firmly in one hand
With your other hand, put your thumb on the center section.
Push DOWNWARD toward the bottom edge following the direction of the arrow, not out, not prying, just straight down.
Use firm pressure, it will suddenly “break free” and slide.
It can takes a bit of force the first time, it’s friction-fit and designed to not slide off easily during basic use.
If it still won’t budge:
Put a rubber glove or cloth on your thumb for grip.
Press harder than you think (seriously, it’s tight by design)
You can also:
Hold the top in one hand
Tap the bottom edge lightly against your palm while pushing down.