Click the Firmware Flasher in Configurator, and select MatekF411 3.5.1 from the drop-down menus in Configurator 10.4.0. Then click Load Firmware [Online]. Click Flash Firmware. (If you encounter some error: please unplug the USB cable, plug it back in, and then click Flash Firmware again.)
3b. For v2 - Flash Custom Firmware
Download custom MatekF411RX 4.0.0 firmware (filename "betaflight_4.0.0_MATEKF411RX.hex") and save it to your desktop.
Connect drone to computer via USB data cable (some are power/charging only). Open Betaflight Configurator 10.5.1. Click Firmware Flasher. Click Load Firmware [Local]. Select the firmware you downloaded. Click Flash Firmware. (If you encounter some error: please unplug the USB cable, plug it back in, and then click Flash Firmware again.)
4. CLI Settings
Open the appropriate CLI dump linked above. (You can also download/save the text file to your desktop.) Select/highlight all of the text within the document and "copy" it (i.e. right-click the highlighted text and select "copy" from your computer's menu). We will "paste" this text in the next step.
In Betaflight Configurator, click the CLI tab in the left-hand column. Right-click on the command line (e.g. "Write your command here"), and select "paste" from your computer's menu. Then press "enter" on your keyboard. The settings should load and save, and then the board should reboot. (Don't worry if you get some kind of serial device error, as it's a known bug which doesn't affect anything.) Disconnect your drone from the USB cable.
5. Binding Drone
Binding the drone to your controller:
For v1, hold the Bind button on the bottom of the board by squeezing the battery mount down onto the button (easier with the lipo battery out of the drone). While holding the button down, plug in the lipo battery. After a few seconds, you can let go of the Bind button.
For v2, plug a charged lipo battery to the drone. The next step is easier if the battery is hanging free, out of the battery mount. Using a non-metallic object (or even just pushing/flexing the battery mount), hold the Bind button on the bottom of the main board for several seconds.
For E6 transmitter on both v1 and v2, turn on your E6 transmitter and then hold the throttle and pitch trim buttons down until there is a slight red LED color showing through the power indicator ring. Keep the E6 transmitter at least 5 feet away from the drone to allow for proper binding. Unplug the lipo battery from the drone. Turn off the E6 transmitter.
For FrSky transmitter, bind your radio transmitter in D8 mode. Keep the transmitter at least 5 feet away from the drone to allow for proper binding. Unplug the lipo battery from the drone. Turn off the transmitter.
(* CLI Method for v2 Only: Use this if forced to bind in D16 (i.e. newer ACCESS-based FrSky radios, but with ACCST16 firmware update). First, change the receiver protocol in the Configurations tab of Betaflight to SPI-based receiver, Frsky_X protocol (which is for D16; the default is Frsky_D for D8). Next, try using CLI commands to bind. Enter into the CLI, "bind_rx_spi" to get into binding mode. Activate the bind function in the transmitter in D16 protocol. The drone's LED's may not change back to blinking, but continue. Then enter into the CLI, "set frsky_x_rx_num". If the rx/receiver number changed to the number that matches the receiver number shown on your transmitter, then the bind was successful. Finally, enter into the CLI, "save".)