try when you´r in black screen use Toolkit to reboot in EDL mode and flash all again: https://forum.xda-developers.com/mi-a2/how-to/mi-a2-toolkit-unlock-bootloader-root-t3834585
remember that`s versions are BETA and maybe is buggy. I use stable 10.0.2.0 and everything is OK, only battery has problem, seems that bug not be fixed
maybe you are entering in EDL mode, are you brick???? or yout trying get out of brick??? anywhere if not show the rabbit, you can try send comands ej: fastboot flash........