Try your code again.
Many Smok codes can take a couple of tries or 0 appears to be an O, etc.
I personally have many Smok products and have yet to have one fail.
Are there better products out there for the same money? Absolutely.
Smok's quality control has suffered from the fact that they produce so many mods they can't seem to stay on top of it.
Smok produces so many products that even though the percentage of unit failure may be the same as other manufacturers, the number is much higher.
You also have to take into account that you're much more likely to hear from disgruntled customers as opposed to satisfied ones.
That being said, I would recommend many other manufacturers way before I recommend Smok.