BIG TREE TECH SKR MINI E3 V2.0 Operation Manual page 9

Shenzhen BIGTREE technology co., LTD.
BIG TREE TECH
8.Connection with BLtouch：
V.The firmware description of motherboard
The factory motherboard is installed equipped with firmware for testing
(model Ender3), which can be used directly or changed according to your
own needs.
1. The Firmware Acquisition Method of Motherboard:
Obtain by Ask customer service or technical personnel;
Download at our Company Open source website:
https://github.com/bigtreetech
2. Motherboard Firmware update method
Choose the file suitable for your model in the downloaded firmware package
to copy to SD Card Root directory.
Note: File name cannot be changed, firmware.bin must be lowercase!
Insert SD card into the main board SD card slot, re-energize or press