Questions about AeroCool Trinity Mini

According to the manual, you can hold down the LED control button for 3 seconds to switch off the LED. (button next to the power button). So you can still plug in the cables.

No, unfortunately they are not controllable. They simply light up in RGB colours when they have power. But you can't control them.

Laut Hersteller nur mATX und Mini ITX. Quelle: https://aerocool.io/product/trinity-mini/

There are actually three fans 2x 140mm and one 120mm, they are RGB.