I restarted at the command pronpt. After that, I was able to launch TWRP with Volume+ & Power, but when img is installed, each folder name changes and MIUI cannnot be started either. Right now, I am rewriting to the original CN rom with Miflash.
Eaven after installing TWRP 3.4.1B and rebooting, the TWRP screen doesnot appear, but it remains a white screen.
If TWRP 3.4.0B is installed and restarted, it will be started with normal MIUI and cannot be enterd in TWRP.