Check if the C201 uses the same method as other Nokia devices. I think Phoenix is the key tool here. Also, maybe include that if the USB detection fails, try different USB ports or cables.
Also, after flashing, the phone might restart automatically. Let the user know that's normal. nokia c201 flash file
Another thing: The user might encounter issues with the firmware package. They need to ensure they're using a .sisx or .nrf file? I think Phoenix uses .nrf files. Maybe include that when downloading, look for the correct file type. Check if the C201 uses the same method
Okay, putting it all together: Sections for prerequisites, step-by-step guide, troubleshooting, warnings. That should cover the user's needs. nokia c201 flash file