Yes this is true, following your instructions @Josh_FP3 I get back to fastboot mode again:
USB connection informations are by the way:
On Windows = Kedacom USB Device (Android Bootloader Interface)
On Linux = Bus 007 Device 127: ID 18d1:d00d Google Inc. Android
After some testing I think I got the EDL mode working. I pressed Volume Up + Down and plugged in the USB cable. The logo flashed shortly and the display is black and I see the device on Windows as “Qualcomm HS-USB QDLoader 9008”.
From this site I installed this tool:
Inside the “QPST Software Download” program I see my FP4 listed as “COM4 Phone in Download Mode” and “Q/QCP-XXX (Sahara Download)”. Is this the right way to continue? I never worked with this software before…
Maybe someone can give me a helping hand here if possible.