Check the charge
A blinking light often indicates a low battery. Charge the device fully and try again.
Check the connection
For pod-based models, remove and reattach the pod so it sits firmly. Wipe the connection points with a clean, dry cloth.
Still not hitting?
Warm the device in your hand for a minute and take a gentle draw. Do not use a sharp object to clear the mouthpiece. Stop using damaged hardware.