Hi Hartmer,
Follow this guide to flash TWRP: https:/ /twrp.me/devices/ xiaomimi5s.html
For fastboot I used this link https:/ /forum.xda-developers.com/ showthread.php?t=2317790
Having TWRP is very handy in case something goes wrong or if you switch rom (linageOS, RR..etc)
Simply install the...