I’d completed a sports climb. Mine was the second ascent so I was to strip the gear on the way down. I attached my sling to one ring of the lower,, threaded the rope and re tied. Ready for descent I discovered that the screwgate carabiner holding my sling to the lower off would not unlock. This left me trapped at the top of the climb. I tried off loading it, tapping the carabiner with my fist and gear to no avail. Neither my partner nor I had a knife to cut the sling with and we were the only climbers at the crag. In the end I bashed the carabiner with a piece of loose rock from the top of the climb and it unlocked, so saving me from dangerous heroics in terms of leaving the harness or an embarrassing rescue call out

The carabiner I’d been using was relatively new and seemed in good condition. Presumably some grit had got into the screw mechanism