Since it's a puff activated
device, my guess is that the activation system got leakage or some sort of condensation on it (inside the parts), whenever this happens the
device won't activate or won't work anymore.
I had a Suorin Air which I gave to my friend and he didn't know how to clean it from the inside. After a while the leakage went inside the draw activation and finally broke, no activation anymore, lights shows on/off and charging fine but won't work anymore. (used about 3 month)
I do wonder of the latest Suorin, whether they are able to fix the leakage getting inside or not. Which of course many auto activation system have leak issue (not all but many) and might break after a while when this happens.