With the halving well behind us and with summer coming I decided it was time to install Braiins OS+ on all my S9's for some more efficient mining.
All my S9's are running the March 2019 firmware from Bitmain that crippled SSH, so I had to use a SD-card to install Braiins.
But about 25% of my S9's are missing the U6 chip behind the SD-card slot, and these machines won't boot from SD.

What is the best way to install Braiins on machines in this situation?