I just bought a Mi box 3 (mdz-16-ab) and anytime I go into settings and select "playback settings" I get a "Unfortunately, Settings has stopped" text box. Anyone else having this problem? I'm on the newest firmware.
Kodi seems to crash frequently too with a similar text box afterwards.
Try resetting to factory defaults. You'll delete everything installed but since you just got it, probably not much to lose.