How to reflash the bootloader on a Fly-E3-v2


This page covers how to reflash the bootloader on a Fly-E3-v2.


These instructions cover flashing with Windows using the STM32CubeProgrammer software. It is possible to use other software, such as DFU-Utils on linux, but they aren’t covered here. You will have to register to be able to download the software.

Connection via DFU

While holding down the reset2, plug in the USB cable into the board and PC.

Fly-E3-v2 DFU Bootloader Button
Fly-E3-v2 DFU Bootloader Button


Launch the STM32CubeProgrammer Software.
Download the bootloader from here.
Select the correct connection method, in this instance its “USB”. You may need to click the refesh button to find it. Then click connect.

Connect via USB

Then click on the “+” icon and find/open the bootloader file you downloaded earlier.

Open File

Click the “Download” button.

Download Bootloader to the board

A “File Download Complete” popup will appear once complete.

Download Complete

Disconnect the board and continue flashing the firmware as normal.