Switch DVR to USB flash mode

  1. Connect USB
  2. Press Reset
  3. Press and Hold MENU
  4. Short press power while holding MENU

Windows should detect device like:

Drivers are inside DirectUSB folder

Windows 10 and unsigned ambarella driver

Flash .elf firmware

  1. Start DirectUSB
  2. Choose Board: a7lbub. Press Connect.
  3. Press EraseNand
  4. Choose .elf firmware file. Check Verify.
  5. Press Download
  6. Reset DVR