Ah, the fact that it started firing just when you plugged in the USB might mean it's not just a connection on the fire button itself. But not for certain, see further on.
I would certainly talk to the vendor first. For any normal product, a month is nothing - returns should be accepted for up to a year at least. Not just on warranty, but also on Fitness For Purpose. We have specific consumer law on that, I'm sure there's something similar in the States; regardless of warranty, a product has to do what it should reasonably be expected to do - for example a washing machine that stops working after a year is not fit for purpose, and can be returned even without an active warranty.
I say "normal products" because vaping does seem to be a bit different, with warranties more like 3 months rather than a year, and only those on the more expensive devices. RBAs and the like usually say specifically no returns, but that's more reasonable because they get soaked in juice and heated up. A mod really should be covered. Whether it is or not is a different matter.
But even if it isn't, the vendor if they're smart should still cover it because they want return sales and a good reputation. That is unless you ordered it direct from China, in which case it wouldn't be worth posting back to them.
If it were mine, I would talk to the vendor first (if in same country), and failing that I'd take it apart and look for any obvious problems around the fire button. The fact that it fired after you plugged in USB doesn't necessarily preclude a problem with the fire button. Maybe the fire is jammed down, such that it started firing until it hit the 10 second cut-off. That cut off meant it wouldn't start firing again automatically, but plugging the USB in basically resets it or at least restarts the timer, hence it fires again for another 10 seconds.
Do you have any experience with electric / electronic devices? Do you own a soldering iron? Do you do any DIY around the house? If the answer to all those is no, then maybe you shouldn't mess with it (I suppose theoretically the wrong repair could make it dangerous.) Otherwise, have a go at it if the vendor return angle doesn't work out.
If you are going to have a go, there's a massive iStick 50W thread in the mods forum where you could ask for advice - I bet there have been a number of people taking theirs apart in that thread already, either to fix problems or to mod it in some way.