Instructions for writing with USB cable (important) Preface Firefly-RK3399 is installed with Android7.1(industry) system by default. Firefly-RK3399 may officially support multiple systems, so it is possible to upgrade firmware for different systems. The firmware of each system has its own version of the upgrade tool. If the version of the upgrade tool is incorrect, the firmware may fail to be upgraded. In particular, pay attention to the cross-system upgrade scenario. This chapter mainly introduces The relationship between system firmware and upgrade tool version and Considerations for cross-system upgrade . The relationship between system firmware and upgrade tool version Download the corresponding version of the upgrade tool according to the table above: Linux_Upgrade_Tool Androidtool_xxx Considerations for cross-system upgrade Explanation of noun "cross-system upgrade": The system firmware to be upgraded and the current system firmware are not part of the same system firmware. Notes Cross-system upgrade firmware generally needs to be erased first , and then upgraded . In addition, the corresponding version of the upgrade tool must be used for both erase and burn. The steps are as follows: Use the corresponding version of the upgrade tool to the current system firmware to erase Use the corresponding version of the upgrade tool to the system firmware to upgrade For example Firefly-RK3399 upgraded Android7.1(industry) firmware by default when it is delivered, and the customer needs to upgrade Android10.0 firmware for example: According to The relationship between system firmware and upgrade tool version , it can be known that: The steps are as follows: Use AndroidTool v2.65 or upgradetool v1.34 to erase Use AndroidTool v2.65 or upgradetool v1.49 to upgrade