Please check that the sd card is really formatted in FAT32 and that the firmware file is named "K2.bin".
What firmware version is currently installed and what version are you trying to flash?
please follow the below steps to try again.
1. Find the firmware version you want to update.
2. Download the firmware to SD card, the SD card which is used for upgrading should be FAT32 format.
3. If your card is in exFAT format, please put this card back to DVR and then connect the APP.
Find the settings on APP, click and find the SD card "format" function, choose it and then the card will be changed to FAT32.
4. After downloading the firmware into the SD card, the name of the firmware must be K2. bin, can not be followed by such Numbers as (1) (2).
5. After the SD card is put into the DVR, it is connected to the power again, and the firmware refresh will start automatically.
That's how the DVR lights flash when it is updating.