: Visit the Napco Technical Library or Napco Access Pro to search for authorized software and firmware downloads.
: Often uses a 16MB SPI Flash (such as the W25Q128) to store the firmware. Download Firmware DVR Napco Hi3521 16Mb Backup rar
To ensure you have the correct and safe firmware, use official manufacturer channels rather than third-party backup files: : Visit the Napco Technical Library or Napco