I was having the same problem and did this. The phone booted to TWRP but then I just tried to reboot it and the phone won't boot, stuck on Mi logo. What gives? What can I do? I don't have any recovery zip in the phone. When booting to TWRP using this method MTP doesn't work.
It works but follow this :
For Twrp after flashing in fastboot mode - when says successfully than type: fastboot reboot (enter) and than hold volume + button and wait ~ 10 seconds until Mi logo is on screen and here is TWRP