Signature 10 limiter red light stays on even with no input
I'm using a Souncraft Signature 10 mixer, it's brand new less than three weeks use and had the limiter on channel one on (button pressed down) and worked fine. Now I'm not using the channel at all, gain set to none (10) all faders set to none, channel even muted, no cable plugged and the red light of the limiter button stays on pressed down or not. Any ideas? Can't find anything on the user guide or online about it? Defect?