unlock & root failed, then flash FTF, but now cannot fastboot boot recovery.img

First time success unlock & use TWRP,
then install SU.zip in TWRP but the phone cannot normal boot in;
therefore flash FTF, now can use the phone but cannot use TWRP again ( fastboot boot recovery.img).
Unlock status is unknown.
Can flash FTF.

What the driver is used in fastboot in Windows?
How can I know the phone is connecting correctly?
Any solution to use TWRP & root? :confused: