Not sure how, i got there once after bootloop. You could try turn phone off, press volume + and - same time, connect USB-cable to computer and release buttons. Phone stays black, but that Qualcomm QHSUSB port should appear in device manager under ports and MiFlash can write rom.EDL mode? Any instructions somewhere?
https://forum.xda-developers.com/redmi-note-3/how-to/guide-reboot-to-edl-mode-fastboot-test-t3398718Try to go over And console.