It seems like the flash was successfull. Different stuff is being flashed/written. I missed some things because it was so fast, but here is what i was able to copy:
Writing bootloader_a...
Restarting device...
Writing bootloader_b...
Restarting device...
Unpacking radio...
Writing radio...
Restarting device...
Unpacking images..
Unpacking boot...
Writing boot...
Writing dtbo...
Writing dtbo...
Writing vendor_boot...
Restarting device...
Error: Failed to execute 'open' on 'USBDevice': Access denied.
The error message is different from time to time. I think i saw 3 different:
- Error: Failed to execute 'transferIn' on 'USBDevice': A transfer error has occurred.
- Error: Failed to execute 'open' on 'USBDevice': Access denied.
- [can't remember and didn't save it]
However, I get to the point where the smartphone shows the GrapheneOS fastboot display: big red "fastbootd".
I can reboot, enter recovery, reboot to bootloader and power off.