Juice can cause all these problems.
Sometimes a good clean and internal dry out can resolve the problems.
Juice, running down the atomizer sides causes the circuit to remain incomplete, and can cause many of the problems you guys are listing here.
If you can flick the front cover off with your finger nail, then thats the best way of drying everything up inside.
Then dry up the atomizer sides, and clean the inside with a Q tip.
Clean all areas with a Q tip, and put everything back in place.
Make sure the atomizer is well connected... fill your cart, add two drops to the atomizer, and if it isnt good to go, after that kind of service, then contact Janty as the switch may be faulty.
Good Luck
Hope it works for you, it has for me, several times.