Flashing a ROM intended for a different sub-model (e.g., A205G on an A205F) will likely hard-brick your device. Always check your device's "About Phone" section or look at the small print on the back cover.
Flashing firmware is an advanced process that carries a risk of bricking your phone if not followed correctly. You are solely responsible for any changes to your device. official samsung galaxy a20 sma205f ds stock rom
Look at the box in the upper left corner. If it turns blue or light blue and displays a COM port number (e.g., 0:[COM3] ), your device is properly connected. If not, reinstall your USB drivers and try a different USB port. Flashing a ROM intended for a different sub-model (e