Most of the time, the red ring flashing means the meat probe is not plugged in and you are trying to cook with a recipe that is based on the internal meat temperature.
If you are certain this is not the case, unplug the unit and plug it back in. At this point, restarting your cook should fix the issue.
Red Light Ring (flashing)
If you see a rapidly flashing red light ring and your smoker is unresponsive, please call customer service at 1-866-239-6777