If default credentials fail, you must force the hardware back to its original settings. Note that this will likely erase your current configurations, though it often leaves recordings intact.
For a visual walkthrough on locating internal components for a manual reset, watch this guide: 01:08 Resetting Multistar DVR Password YouTube• Dec 5, 2023 how to reset multistar dvr password
October 26, 2023 Subject: Methods for Resetting Forgotten Passwords on Multistar Digital Video Recorders (DVR) If default credentials fail, you must force the