This phenomenon is that there is something wrong with the lock of the upper handle, and the floating valve may be stuck. It is imperative to open the lid first. When I deal with this problem, I always use a Phillips screwdriver to unscrew the fixing screw from the lower handle and take off the lower handle, so that the lock doesn't work. Just open the lid. When doing this step, be sure that there is no pressure in the pressure cooker before opening the lid. Then put your hands back. If it's convenient, take photos of the front and back of your upper handle and lid, and I'll teach you how to handle it. Try again and see if you can get back to normal next time. I have worked as a senior R&D engineer of pressure cooker, and I believe I can help you put forward effective solutions.