fastboot flash recovery twrp_phoenix_k30_3.3.1_06-01-2020_dtbo.img
fastboot boot twrp_phoenix_k30_3.3.1_06-01-2020_dtbo.img (or presspower + vol +)
Result: There are no errors. But the screen only shows a black color without booting into TWRP. Rebooting, the smartphone is still on the main...