Most washing machines have a timer that prevents you from opening the hatch just after the washing cycle ends. Instad you must wait for the timer to go off, usually a minute or two, before you can open the hatch.
Why? Would letting the user open the hatch immediately after washing ends pose any safety or other issues?
Maybe that’s your machine being oddly programmed. Every machine I’ve seen unlocks right after it finishes it’s cycle. It can also be stopped and unlocked anywhere halfway, but it takes some time to drain the water (usually a few seconds, not a full minute like you mentioned originally).