GMMK Pro Restores to Original Firmware from VIA

Minimal guide how to flash GMMK Pro keyboard from factory firmware to VIA firmware and vice versa.

Factory firmware to VIA firmware

Download VIA firmware
Download QMK Toolbox
Unplug your keyboard and reconnect it while holding the spacebar and B at the same time
You should see a message in the QMK Toolbox that indicates that your board is in STM DFU Bootloader Mode.
Load the VIA firmware and press Flash

VIA firmware to factory firmware

Download factory firmware (Backup)
Unplug your keyboard and reconnect it while holding the ESC (The official guide is wrong that tells you to hold spacebar and B)
You should see a message in the QMK Toolbox that indicates that your board is in STM DFU Bootloader Mode.
Load the factory firmware and press Flash