I don't know how to open this, detail is shown in pic.
Plz tell me if you have a clue, thank you in advance.
How to open a lock without handle?(with pic)
lock
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That spring is definitely broken. It sits in the square bracket and pushes against the lever above it.
Do you have another working handle that you can disassemble to compare to?
If I am inferring correctly what you are describing, it sounds like the "brains" of the system are installed outside with one screw access. That, of course, is an abysmal design. The only thing that should be outside accessible would be the wires to the call button and speaker - all other wiring should be inside-access only.
If you are otherwise happy with the system, you could probably move the components that should not be outside inside, leaving only the wiring needed for the outside components running to the outside box.
Best Answer
Now I have solved the issue. The mechanism is in a reserved direction. To open the door, I need to push towards the latchbolt direction instead of the hinge side. Guess my lock is bit of different from others. Thank you guys for your helpful advice.