robin_nano35_cfg.txt is the config file. Firmware came from here: https://github.com/makerbase-mks/MKS-Robin-Nano-V1.X/tree/master/Nano%20firmware%20v1.x.x/nano35 Copy txt file to SD card to update.
vi robin_nano35_cfg.txt; cp robin_nano35_cfg.txt /Volumes/NO\ NAME/robin_nano35_cfg.txt; diskutil unmountDisk /dev/disk5
sys/ contains all config files. Firmware came from https://teamgloomy.github.io/index.html