Extract the update tool and make it available to the list of programs that the user can execute:
tar xf Linux_Upgrade_Tool_v1.2.tar.gz
cd Linux_Upgrade_Tool_v1.2
sudo mv upgrade_tool /usr/local/bin
sudo chown root:root /usr/local/bin/upgrade_tool
Power on Firefly-RK3288.
Use micro USB OTG cable to connect Firefly-RK3288 to the personal computer.
Press and hold RECOVERY hardware button. After that shortly press RESET hardware button and after two seconds release RECOVERY.
Flash the new bootloader:sudo upgrade_tool ul RK3288Loader_uboot_V2.17.02.bin