Help With Red Dot Sight

[Duppy]

I recently got a red dot sight ( https://www.taiwangun.com/red-dot-sights/mini-red-dot-sight-black-pcs ) and I'm not sure how to get it working, I don't know if I'm doing something wrong or it's broken, i'm very new to airsoft.

[Guest]

The switch on the back. Does it have a good battery in it?

[Samurai]

There's two large screws, looking from the top, that you must undo. The whole upper part separates and there is where the battery goes.