Midas M32R - one XLR input shows signal with nothing connected


XLR Input 7 on my Midas M32R is suddenly showing a constant signal with nothing connected, pic attached. I updated to the latest firmware, did a factory reset, tried reseating the USB card, cleared every routing, etc. etc. Does anyone know what might be causing it and whether it's possible for me to fix it? Maybe opening the unit and cleaning it? Unfortunately it's out of warranty at this point. Any help greatly appreciated.