|The following is based on Fallout: Brotherhood of Steel and has not been confirmed by canon sources.|
Destroy the automated gun turrets guarding the vault entrance. HINT: You can destroy the turrets directly, or destroy nearby machinery to de-activate them.”— In-game description
There are a total of eight of them guarding the entrance to the Secret Vault, and special power sources are used to maintain them in working condition. These sources can be considered the system's weak spot. There are more of these systems inside the Vault.
When the Initiate of the Brotherhood of Steel makes his way to the Vault's entrance, some dumb super mutants accidentally activate the system. However, the Initiate manages to destroy all eight turret Robots and their power sources, unlocking the doors. Later, he battled some more robot turrets guarding the Vault's facilities and laboratories. On few occasions, the Initiate could even take control of a robot turret to kill some super mutants.