I just purchased a brand new sealed in box Helix LT. the software was version 2.3 so before I ever plugged a guitar in I updated the firmware to 2.81. Once completed I plugged in and found I have no input from guitar. I have checked the guitar and cable and it is not them. When I put on the tuner in the Helix it gets no signal. I also have tried reinstalling the firmware. Does anyone have any experience with this issue?