Did you get it wet, by chance? The reason I ask is because I just recently got mine wet, and it started to fire by itself. It did so beyond the 5 second cut off, and would not fire at all after drying it off. I took mine apart, months ago, to do the pin short trick to get it to light up again as it had went into a soft brick mode.
I'd recommend against doing this if it is still under warranty, because it will void the warranty. I had bought it secondhand off of the guy at my local vape shop that was quitting, so I wasn't worried if I voided it due to getting it for so cheap.
Anyway, I took it apart again last night to rub the board down with alcohol to make sure I got rid of any moisture that could be causing a short. What I found was that something on the board had gotten so hot that it had leaked whatever "fluid" that was inside of it out on to the board, and it was covering quite a few solder points.
I'm guessing it was a capacitor, but I'm not completely sure. Nothing stuck out as obvious. After reassembling the device, I tried to fire it again. I had the purple light of death. An interesting find was that I could connect it to my computer, launch the escribe software, go to device monitor, and use the on-screen buttons (revealed by hitting the tiny button on the left of the "puff" button) to unlock the device. The device's button did the same thing as yours, but by clicking on and holding down the on-screen fire button, I was able to puff on it just like I would normally with the device's button.
Nothing I did fixed it, no matter how many times I cleaned it, rebooted it, or pressed the buttons. It held me over until I could get by the shop to grab me another today. Luckily, I had enough points built at the vape shop to take some of the sting out of a new one, but I still dropped close to $50. It wasn't ideal, but neither is doing without it whenever you want it!
I'm going to keep messing with the other one to see if I can fix it, but I don't have a lot of confidence in this repair. If it's not a bad component on the board, then it's a bad trace within it. I'll probably try to reflow it in the oven or with a heat gun.
That's probably way more than you wanted to hear, but that's what I've found to be the cause of mine. Hope that helps some.