Hello, I flashed a GSI ROM onto my Hi 9 Pro (using PHH Treble v123 worked, but all the hardware buttons disappeared. I tried to jump to the Android 10 versions unsuccessfully). Now the system no longer is able to boot normally, to enter fastboot, or recovery. If you press volume and power, then select the option, the screen turns black.
I don’t really understand how to operate SPFlashtool. There are references to scatter files which I don’t know where to find.