Steps

Change the motherboard

1. Turn if off and unplug it
2. Remove 2 screws on top and 3 on the bottom of motherboard protector block
3. Take photo of connections to be able to rool back if needed
4. Unplug all from old and plug it back in the new one
5. /!\ Normally, all connections will be all at the same place, except for the Fan, because it will be inverted (so on the FAN 0 and not the 1)!
6. Put 2 screws on top and 3 on the bottom of motherboard protector block

Create your firmware

1. Download and install VSCode from Official Visualstudio
2. On VSCode interface, in the left side menu, add useful extensions:
3. AutoBuildMarlin
4. PlatformIO IDE
5. PlatformIO IDE -> Import Marlin_SKR_E3_Mini_12_512K project from Official Github
6. Reddit source: https://www.reddit.com/r/ender3/comments/dsmf6x/512k_flash_working_on_skr_mini_e3_v12/
7. Github original: https://github.com/bigtreetech/BIGTREETECH-SKR-mini-E3/tree/master/firmware/V1.2
8. /!\ This version is already custom: so 512K memory (more than normal to be able to support full options, optimisation settings, etc.)!
9. Edit (if needed):
10. platformio.ini
11. Marlin -> Configuration.h
12. Marlin -> Configuration_adv.h
13. Click on the "check symbol" in the bottom taskbar to start the build
14. Go on the "Marlin_SKR_E3_Mini_12_512K-bugfix-2.0.x\.pio\build\STM32F103RC_bigtree_512K\" folder to check if your have the "firmware.bin" file

Update firmware

1. Copy paste "firmware.bin" file at your microSD Card root
2. Shutdown printer
3. Put microSD Card
4. Turn on and wait the motherboard red led inside stop blinking
5. Remove microSD Card
6. Put it back in your PC
7. If it worked, you will have "FIRMWARE.CUR" at your microSD Card root, otherwise you have try to flash a wrong file

Known issues

1. > If you have your printer crash (non stop buzzer sound, stop printing, etc.) when you put the USB with Cura:
2. Go to "C:\Program Files\Ultimaker Cura 4.4\plugins\USBPrinting" folder
3. /!\ Ultimaker Cura 4.4 is my version, but yours can be newer!
4. Open "AutoDetectBaudJob.py" file (in administrator mode to be able to edit it)
5. Comment out following lines to have:
6. #try:
7. # programmer.connect(self._serial_port)
8. # serial = programmer.leaveISP()
9. #except ispBase.IspError:
10. # programmer.close()