Newbie here. Need some troubleshooting help. I have a GW Instek GPD-3303S that started giving me some trouble. when I press the output button for a preset voltage/current for channel 1, channel 1 goes to 0V, 0A. Any idea why this is happening? The other channel works just fine. I don't see the OV LED coming on either. I might be missing something very trivial, but appreciate any help with troubleshooting this. Thanks!