Just used my iSi for the first time, made a yogurt/cream based liquid, no chunky parts. Charged whipper as per instructions, shook a few times. Whipper got cold as gas went in, eg I think the gas made it in. Now I press the handle, and nothing happens except a few drops of the liquid come out.
I figured I'd try again, but no matter how I hold the bottle and press the handle, gas doesn't seem to release. So now I have a pressurised bottle that I think I probably shouldn't open...or should I try to gently unscrew the head? What's the worst thing that can happen, other than a messy kitchen? How much pressure is involved? Anything else I could try?