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Hello everyone.I wanted downgrade Catalina to Mojave. What I've done:1. I created Mojave bootable flash.2. Enter to recovery mode and erase main disk.3. Next restarted Mac to boot from the flash.But system did't boot from flash. The system offered to "Starting Internet Recovery" from the WIFI. After the download progress reached 100%, the system showed icon with exclamation mark and message "apple.com/support -9000F". Now Mac does't boot from a any external drive, does't started in Recovery mode, I used ⌘-R and Option-⌘-R and Shift-Option-⌘-R and Options for select boot disk but Mac over and over again downloads something from the Internet and shows this error over and over again. I'm have a serious problem what should I do?