The blinking means it's time to replace your filters! Don’t forget, there is one filter on each side.
Purchase HATHASPACE Certified Replacement Filter for HSP003 Dual Filtration HEPA Air Purifier, 1 Set (H13 True HEPA). Each set comes with 2 filters.
After you have changed the filters press the “Timer” and “Sleep” buttons together and hold for 3 seconds to reset the blinking light.