Red Light (and no beep) = Possible scan error.
If after a scan the machine flashes a single red light, you may have scanned the wrong tag. Wait for the
round white light to come back on, press the round sensor, and scan again.
All lights are turn red after roasting: If all lights on the machine turn red on plug-in, the machine may simply need to cool down after its last roast. It's best to wait for 20minutes, but otherwise, wait for the red lights to turn off and switch to a pulsing white light before starting your next pot of coffee.