The Unofficial JGMaker (& JGAurora) Wiki

In some circumstances, a firmware flash may fail half way, which will cause the motherboard to “lose” its bootloader. The bootloader is a part of the firmware that allows the motherboard to be upgraded over USB. Without the bootloader, the firmware must be flashed using the ICSP programming port.

The bootloader can be reinstalled using either a USB programmer device, or using an arduino device.

Please read this article first for the main guide. We need to do three things:

1. Install the bootloader flashing sketch onto the arduino device you will be using, using USB cable from computer to arduino
2. Connect the cables between arduino and the MKS motherboard in the A5
3. Flash the bootloader using the Arduino IDE software.

For step 1, you need to flash the programming sketch to the arduino. See “Load the sketch” at the link above.

For step 2, you need to wire up the device. See the link above if you have an arduino uno, or nano. If you have an arduino MEGA, the pins are different - use the wiring here]

You may have to connect a jumper from ground to reset on the arduino, to prevent it being reset during flashing.

for step 3, make sure to cross your fingers and toes.

Once you have flashed the bootloader, you can flash the firmware using your usb cable directly to the printer. Don't forget to follow all the instructions!