What I suggest you do, is to get someone to press down on the front edge of the bonnet while you pull the release lever. If the bonnet then opens, it's a matter of adjusting the prong that goes down into the hole that you pictured. The prong has a cutout in the end for a screw driver, and there is a lock nut at the point where it enters the bonnet. Loosen the lock nut and try turning the prong to the left, say half a turn, tighten the lock nut, and see if that makes any difference. Continue doing that a couple of times. You might need to experiment until you find a position where the bonnet opens properly and still closes with a snug fit.