I have flashed the firmware without any issues. After rebooting the board, the modem won’t be detected anymore. I have noticed that if the same modem is plugged into the M.2 B-key socket through a B-key to mPCIe converter, the modem works. So the the new firmware causes issues with the mPCIe socket of my board. Please investigate.
I’ve initially reported the modem not being detected anymore here.