USB driver issues
The first thing, you should install the USB driver! And you'll find the COM port in your computer's device manager.
1. Cannot upload the firmware to the board
Sometimes the firmware is compiled successfully but just can’t upload it to the board, in this case you can unplugged all the other parts on the board and try to upload it again.
2. The driver is not well installed
If your COM port show the same information as the picture shows, it seems the driver is not well installed. Try to reinstall it like this, and remember to select the correct COM port and motherboard in your arduino.
step01: step02: step03:
step04: After this you can try to connect to your PC again see if it works.