We made this easy to follow guide to help you with installing the firmware so you can start using the PC interface immediately.
Step 1: Download New Firmware
Once you've downloaded and installed the PC interface HERE and the FTDI drivers HERE for your multirotor programmer (BLH7840) you will need to select the "download new firmware" link on the first screen that pops up on the PC interface. See photo.
Install the firmware that you just downloaded but clicking the "install it" button highlighted in the picture below. Make sure you save it to a place that you can easily access such as your desktop.
The next screen you will see is the firmware update installer screen. Here you will need to select the firmware file. Its likely that the program will automatically find the file for you, but you may have to select the "..." button to choose the firmware file you just downloaded. After that, you need to select the correct COM port that your USB multirotor programmer cable is plugged into. Here you see that ours was defaulted on COM 3 but needed to be on COM 14.
Once you have these two things selected, go ahead and hit update.
You will now see this screen. Make sure your 350 QX is plugged into the multirotor programmer cable and is not powered up. After you have it plugged in and you see this screen, you can now power on the model to begin the update.
This is the screen you will see when you fire up your 350 QX by turning on the switch. The firmware file should automatically start downloading. Make sure not to turn off your PC or the 350 QX during this process. If you don't see this screen pop up, its likely that you have the wrong COM port selected and should go back the the previous screen to correct that.
When the firmware update completes, you will see this screen. You can now restart the 350 QX by cycling the switch.
Once you cycle power, you will see the PC interface working properly! You've just completed the update! Make sure that you've adjusted your radio program to the new QX3 settings as some of the functions have changed.