Loud banging, nozzle crashing

Qidi printers have sensorless homing. Stepper motors can detect when the printhead stalls and tells the printer it hits something

Doing bed leveling from screen and after it finishes sending "bed calibrate" from Fluidd. It's Klipper error and will cause bed to crash into printhead
When trying to level the bed or start a print, but you don't have flex sheet on. Printer will rise the bed and since there's no sheet probe won't detect the bed and keep rising it even after it collides with printhead. Eventually Klipper will detect that something is off and stop the movement. It's still going to be scary loud grinding noise for some seconds
Rushing through the on-printer screen. It's rather slow. There might be cases where you think command didn't went through but it actually did. Now pressing something again might cause multiple unintended commands to be sent