This is pure speculation on my part, but I would try pulling the slide all the way to the rear and lifting the rear of the slide straight up. Make sure the gun is unloaded, chamber clear, magazine out of the weapon. Cock the hammer before pulling the slide back because it will make pulling it back easier. There is probably a take-down lever on one side somewhere that needs to be rotated. My Bersa .380 breaks down in the above manner and I have had one other than was the same way. Good luck.