Favicon help in 42k theme

I tried to upload a favicon (42k theme) following these instructions – https://factory42.co.uk/changing-the-favicon/, uploading the favicon to the specified folder w/ FTP. I even tried to change my header php. Cleared my browser cache, tried 2 different browsers – it’s still either showing the old favicon, or none, or the old one in one browser and none in the other….any other troubleshooting ideas?