A red light on top of the feeder is a warning indicator and will appear if the feeder is jammed or if it is empty.
To fix any food jam remove the inner food bin and empty the contents. Reinsert the food bin again and press the set button once and observe that the dispenser turns.
If the red light remains on and the bin is not empty you may need to recalibrate the weight sensor. To do this empty the food bin and return the empty bin to the feeder. Using the app, navigate to the device page and choose the settings icon in the top right. Then select "Weight Sensor" and press "Reset Weight to Zero". Once complete you can refill the food bin again.