If you have gone through the basic troubleshooting ideas concerning problematic channels, including doing a Factory Rest on your mixer with the same results, you would want to read on this page how to setup repair your StudioLive unit through our repair facilities in the US or in other countries.
Factory Reset instructions for classic and AI mixers are found below:
StudioLive AI Mixer Firmware Recovery - Factory Reset
How to reset your mixer to Factory defaults - Factory Reset
StudioLive RM series Firmware Recovery - Factory Reset