Deep in a verified engineering forum, he found it: a single, cryptic link titled
(to ensure the 16Mb flash chip matches)
If you share the , I can guide you through the recovery steps. Download Firmware DVR Dahua DHI HCVR5116HS 16Mb Backup rar
(boot loop, black screen, or forgotten password) Your preferred flashing method (USB tool, TFTP, or RS232) Deep in a verified engineering forum, he found