Do you have a USB-TTL adapter? Can you check whether there is any output information under the serial port check? If there is no output information, it is likely that the device has not burned the program.
Do you have a usb-ttl Adapter? Can you check whether there is output information on the serial port? If there is no output information, it is likely that the device does not have a burning program.
Do you have a USB-TTL adapter? Can you check whether there is any output information under the serial port? If there is no output information, it is likely that the device has no burning program.