Control unit flashing

Usually the blue led of the small unit that drives the strip is switched on. What does mean when the blue led is flashing (and the leds of the strip are switched off)?

My Yeelight was working fine for the past 6 months. Suddenly the control unit started to flash blue light and the light is out of control with the app. Tried to reset but it will end up flashing blue light at control unit. Anyone csm help?