Also, after flashing, the phone might restart automatically. Let the user know that's normal.

Wait, the user might not have the firmware file yet. Maybe lead them to download it from official or trusted sites. But I shouldn't recommend specific sites due to policies. So just mention they can search for it but need to verify the source.

Wait, the user might not know how to enter service mode. For Nokia devices, it's usually done by holding certain buttons during boot. But maybe the guide should specify that. For example, holding the menu button while connecting to PC. Or is there a specific key combination? I need to verify that. Let me recall: For C201, to enter service mode, hold Volume Down + C button (assuming it has that button) and connect to PC via USB. But I'm not 100% sure. Maybe check a reliable source. Alternatively, mention that service mode is entered by pressing specific keys during USB connection.