EC200U Flash Error

Hi Everyone,
I am currently using the EC200U Quectel board. There I am programmed for UART to communicate with STM32. So I develop one Program and the Compilation process was also successfully completed and also I’m using the Qflash v5.4 tool to dump the program to the board. But the issue with that is I can’t able to download the compiled file to the board. It shows the Error message as

                  [COM0]Download Fail[Open Port Fail]!

I’m choosing the correct baud rate and the port but I can’t dumb it. Please help me to do this.

Hi Saran
Please send at+qdownload=1 through the USB AT port first, and then use the output port to burn the .pac file. Baud rate can be selected as 921600