Format a USB/SD card to FAT32, create a folder named "ec900_img". 2. Place the official firmware (.img) and md5.txt (containing the firmware’s MD5 hash) into the folder. 3. Insert the USB/SD card into the EC942. 4. The device will auto-verify and upgrade – WARN/ERROR lights will indicate progress. 5. Upgrade is complete when the lights return to normal; check the log file in "ec900_img" for confirmation.