Similar bad thing happened to me. I got a flat and hadn't used my CO2 inflator but once - and that was to fix someone else's flat. It was a Lezyne trigger and it was jammed and wouldn't open. It finally did and stuck open so I lost all of the charge. Luckily I had a hand pump that got me going. But later inspection of the trigger head OI found the o-ring was missing. This seems a common problem and I guess I lost that on first use.

So I got a different inflator and I check these things often now since I don't always carry a hand-pump.

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