It is much much easier to kill a mod than it would appear at first... In the last four months, I managed to destroy:
Three Cigpet Ant (pico-sized); two died from a three-feet fall to hard floor, and one went up in smoke on its own accord.
One Sigelei J150, the internal battery -which had seen two months of use- swelled and popped the cover apart; it happened after a short flight.
One week-old Smok R80, first the 510 pin cracked and popped out; I was able to fix it with a drop of solder, but after one day, the charging port come off the PCB, peeling the copper tracks meanwhile.
One ML class, which had seen one year of daily use, had a big leak from the clearo while charging overnight; the micro-USB port and associated PCB copper tracks were destroyed by the electrolytic corrosion. The ML has been the only one of the bunch which I rushed and bought anew.
So in order of mod kill ability, we have: Impact by a fall, even a short one; e-liquid leaks from the tank, which are unforgiving if the mod is charging; and poor build material / insufficient building craftsmanship. The three main cause of premature mod death, in my experience.