Stock Firmwares:
S60: Download
S65: Download

S65-Plus: Download

How to configure your own layout:
1. Download your keyboard's .json file:

2. Go to this site:
3. Click upload and select the file you just downloaded.

4. Configure your own layout! Note: You should leave the wiring, pins, and settings tabs alone unless you know what you're doing.
5. Once you're done, go to the compile tab and click Download .hex.
6. You're done, now just flash it to your keyboard.