You can click one or many buttons a at once, it doesn't matter. If something doesn't light up, it doesn't work on your mouse.
- Test doesn't work at all.
- Side mouse buttons are swapped
It's ok, some mouses like A4tech X7 have "back" and "forward" functions swapped.
- Side buttons don't light up
This can happen on modern Firefox or on some very outdated browser. Just use Chrome or Edge for this test to be sure these buttons work.