Please follow up the below video to upgrade the DVR:
The below is the detail steps to upgrade the DVR:
(1). You needn't open the upgrade file, please directly download the upgrade file
and save it to your U-disk.
(Please save the upgrade file rootfs-3520dv300 in the root directory, not save it under any other folders.)
Note: it is better to use a 16GB or smaller flash drive with a Fat32 format.
(2). The file's name should be rootfs-3520dv300, can not be have any changes,
if the file's name change to rootfs-3520dv300(1), the upgrade will be failed.
(3). Before starting to upgrade, please remove the mouse and unplug the power supply,
then plug the U-disk into the DVR's USB port, and plug the power supply.
(4). It can upgrade automatically as long as it has electricity, the upgrade process need
to last several minutes, please be patient.
After upgraded, Please go to the DVR’s main menu – information – System to check the version.
If the upgrade was failed, we suggest you change another U-disk or USB port to try.
Please don't worry, if this can't help you, please feel free to contact us.