Identify the exact SUNMI model and current firmware version
Back up all data and configuration settings
Download the correct official firmware package for the exact model
Verify the firmware file integrity if a checksum is provided
Charge the device fully or connect it to stable power
Turn off the device
Enter the device’s recovery or flashing mode using the model-specific key combination
Connect the device to the flashing tool or PC if required
Open the official SUNMI flashing utility or approved service tool
Load the firmware package into the tool
Select the correct device port or connection mode
Start the flashing process
Do not disconnect power or cable during flashing
Wait until the process completes successfully
Reboot the device when prompted
Perform a factory reset if required by the firmware instructions
Reconfigure the device and restore backed-up data
Confirm the new firmware version after startup