Hi,
I tested around with my board and to make it short it does not boot anymore.
So the only way to get it working again is to hardware flash it.
On the libreboot website a beaglebone board is recommended to flash and there
is also some documentation:
https://libreboot.org/docs/install/ga-g41m-es2l.html
"You can only externally reprogram one of the chips at a time, and you need
to disable the chip that you’re not flashing, by connecting 3v3 to /CS of
that chip, so you will actually need 2 test clips (you also need to connect
GND on the chip that you’re disabling)."
What does connecting 3v3 means and what is /CS?