Beside this seemingly unremarkable door was a row of number buttons from 0 to 9, laid out like elevator buttons from the 21st century.
All the buttons were solid metal ones.
When pressed, the mechanical structure was palpable, requiring significant effort; relying solely on human arm strength wasn't enough, and assistance from armor was needed to exert force.
Both the door and the adjacent alloy wall, along with the surface of the number buttons, were coated with neutron material, making it nearly impossible to damage them externally.
This was a purely mechanical numeric password lock. It was primitive, ancient, structurally simple, with an even simpler principle.
Moreover, the password lock appeared out of place with the wall.
Ren Zhong speculated that this was likely a control door lock substitution thought up by the frozen elders after losing "the Net."
Although simple, the solution was reliable and stable.
