If software methods fail, you can try a hardware-level reset.
Reinsert the battery, close the casing, and power up the system.
Open your DVR’s mobile companion app (e.g., XMeye, gCMOB, Hik-Connect). Go to the settings menu and select . Scan the QR code with your phone camera.
Older generations of AHD DVRs rely on a small coin-cell battery to keep the internal clock running when the power is disconnected. Removing this battery resets the system time, which can break the password lock or revert it to default. Steps for Battery Reset: Power off the DVR and open the chassis cover.